Steve Dower

27 exploits Active since Jun 2019
CVE-2026-2297 WRITEUP MEDIUM WRITEUP
CPython < 3.15.0a7 - Unprotected User Data Exposure via SourcelessFileLoader Import Hook
The import hook in CPython that handles legacy *.pyc files (SourcelessFileLoader) is incorrectly handled in FileLoader (a base class) and so does not use io.open_code() to read the .pyc files. sys.audit handlers for this audit event therefore do not fire.
CVE-2026-12003 WRITEUP MEDIUM WRITEUP
CPython >3.11 Insecure Input Validation resulting in privilege escalation
To allow builds of Python to be run from an in-tree layout (rather than an installed file layout), the VPATH variable is defined at build time and used to locate certain landmarks - specifically, Modules/setup.local. When this landmark is found relative to VPATH relative to the executable, Python assumes it is running in a source tree and generates a different default sys.path. This code remains in release builds, so that release-ready builds can be built in-tree. On Windows, since builds are written to 'PCbuild/', the value of VPATH is set to '..\..', which results in a landmark of '..\..\Modules\setup.local'. This path is outside the install directory of Python, and may have different permissions, potentially allowing a low-privilege user to create the landmark and an alternative `Lib` folder that will be discovered by an otherwise restricted install. Such a setup occurs with the legacy default install location for all users (in the now superseded EXE installer), due to how Windows allows all users to create folders in the root directory of their OS drive. Our recommended mitigation on Windows is to migrate away from the legacy installer and use the new [Python install manager](https://www.python.org/downloads/latest/pymanager/) to install for the current user. Installs where the directory two levels above the Python installation directory have equivalent permissions are unaffected (in general, a per-user install cannot be modified at all by other users, removing any escalation of privilege risk, and could be directly modified by a privileged user, making the potential tampering irrelevant). Alternative mitigations might include preemptively creating and restricting access to a `Modules` directory. Be aware that only 3.13 and 3.14 will receive updated legacy installers - earlier fixes are only provided as sources. Platforms other than Windows allow VPATH to be overridden, but as they don't usually use a separated directory in the build for binaries, are unlikely to have a landmark reference outside of the install directory. The landmark detection involving VPATH is a fallback for when a more specific landmark - .\pybuilddir.txt - is absent, and was included for compatibility. Future releases of Python will no longer include the fallback, and so builds will need to generate or preserve the pybuilddir.txt file in order to work in-tree. This landmark file has been generated on Windows since 3.11, and on other platforms for longer.
CVE-2026-12003 WRITEUP MEDIUM WRITEUP
CPython >3.11 Insecure Input Validation resulting in privilege escalation
To allow builds of Python to be run from an in-tree layout (rather than an installed file layout), the VPATH variable is defined at build time and used to locate certain landmarks - specifically, Modules/setup.local. When this landmark is found relative to VPATH relative to the executable, Python assumes it is running in a source tree and generates a different default sys.path. This code remains in release builds, so that release-ready builds can be built in-tree. On Windows, since builds are written to 'PCbuild/', the value of VPATH is set to '..\..', which results in a landmark of '..\..\Modules\setup.local'. This path is outside the install directory of Python, and may have different permissions, potentially allowing a low-privilege user to create the landmark and an alternative `Lib` folder that will be discovered by an otherwise restricted install. Such a setup occurs with the legacy default install location for all users (in the now superseded EXE installer), due to how Windows allows all users to create folders in the root directory of their OS drive. Our recommended mitigation on Windows is to migrate away from the legacy installer and use the new [Python install manager](https://www.python.org/downloads/latest/pymanager/) to install for the current user. Installs where the directory two levels above the Python installation directory have equivalent permissions are unaffected (in general, a per-user install cannot be modified at all by other users, removing any escalation of privilege risk, and could be directly modified by a privileged user, making the potential tampering irrelevant). Alternative mitigations might include preemptively creating and restricting access to a `Modules` directory. Be aware that only 3.13 and 3.14 will receive updated legacy installers - earlier fixes are only provided as sources. Platforms other than Windows allow VPATH to be overridden, but as they don't usually use a separated directory in the build for binaries, are unlikely to have a landmark reference outside of the install directory. The landmark detection involving VPATH is a fallback for when a more specific landmark - .\pybuilddir.txt - is absent, and was included for compatibility. Future releases of Python will no longer include the fallback, and so builds will need to generate or preserve the pybuilddir.txt file in order to work in-tree. This landmark file has been generated on Windows since 3.11, and on other platforms for longer.
CVE-2026-12003 WRITEUP MEDIUM WRITEUP
CPython >3.11 Insecure Input Validation resulting in privilege escalation
To allow builds of Python to be run from an in-tree layout (rather than an installed file layout), the VPATH variable is defined at build time and used to locate certain landmarks - specifically, Modules/setup.local. When this landmark is found relative to VPATH relative to the executable, Python assumes it is running in a source tree and generates a different default sys.path. This code remains in release builds, so that release-ready builds can be built in-tree. On Windows, since builds are written to 'PCbuild/', the value of VPATH is set to '..\..', which results in a landmark of '..\..\Modules\setup.local'. This path is outside the install directory of Python, and may have different permissions, potentially allowing a low-privilege user to create the landmark and an alternative `Lib` folder that will be discovered by an otherwise restricted install. Such a setup occurs with the legacy default install location for all users (in the now superseded EXE installer), due to how Windows allows all users to create folders in the root directory of their OS drive. Our recommended mitigation on Windows is to migrate away from the legacy installer and use the new [Python install manager](https://www.python.org/downloads/latest/pymanager/) to install for the current user. Installs where the directory two levels above the Python installation directory have equivalent permissions are unaffected (in general, a per-user install cannot be modified at all by other users, removing any escalation of privilege risk, and could be directly modified by a privileged user, making the potential tampering irrelevant). Alternative mitigations might include preemptively creating and restricting access to a `Modules` directory. Be aware that only 3.13 and 3.14 will receive updated legacy installers - earlier fixes are only provided as sources. Platforms other than Windows allow VPATH to be overridden, but as they don't usually use a separated directory in the build for binaries, are unlikely to have a landmark reference outside of the install directory. The landmark detection involving VPATH is a fallback for when a more specific landmark - .\pybuilddir.txt - is absent, and was included for compatibility. Future releases of Python will no longer include the fallback, and so builds will need to generate or preserve the pybuilddir.txt file in order to work in-tree. This landmark file has been generated on Windows since 3.11, and on other platforms for longer.
CVE-2026-12003 WRITEUP MEDIUM WRITEUP
CPython >3.11 Insecure Input Validation resulting in privilege escalation
To allow builds of Python to be run from an in-tree layout (rather than an installed file layout), the VPATH variable is defined at build time and used to locate certain landmarks - specifically, Modules/setup.local. When this landmark is found relative to VPATH relative to the executable, Python assumes it is running in a source tree and generates a different default sys.path. This code remains in release builds, so that release-ready builds can be built in-tree. On Windows, since builds are written to 'PCbuild/', the value of VPATH is set to '..\..', which results in a landmark of '..\..\Modules\setup.local'. This path is outside the install directory of Python, and may have different permissions, potentially allowing a low-privilege user to create the landmark and an alternative `Lib` folder that will be discovered by an otherwise restricted install. Such a setup occurs with the legacy default install location for all users (in the now superseded EXE installer), due to how Windows allows all users to create folders in the root directory of their OS drive. Our recommended mitigation on Windows is to migrate away from the legacy installer and use the new [Python install manager](https://www.python.org/downloads/latest/pymanager/) to install for the current user. Installs where the directory two levels above the Python installation directory have equivalent permissions are unaffected (in general, a per-user install cannot be modified at all by other users, removing any escalation of privilege risk, and could be directly modified by a privileged user, making the potential tampering irrelevant). Alternative mitigations might include preemptively creating and restricting access to a `Modules` directory. Be aware that only 3.13 and 3.14 will receive updated legacy installers - earlier fixes are only provided as sources. Platforms other than Windows allow VPATH to be overridden, but as they don't usually use a separated directory in the build for binaries, are unlikely to have a landmark reference outside of the install directory. The landmark detection involving VPATH is a fallback for when a more specific landmark - .\pybuilddir.txt - is absent, and was included for compatibility. Future releases of Python will no longer include the fallback, and so builds will need to generate or preserve the pybuilddir.txt file in order to work in-tree. This landmark file has been generated on Windows since 3.11, and on other platforms for longer.
CVE-2026-12003 WRITEUP MEDIUM WRITEUP
CPython >3.11 Insecure Input Validation resulting in privilege escalation
To allow builds of Python to be run from an in-tree layout (rather than an installed file layout), the VPATH variable is defined at build time and used to locate certain landmarks - specifically, Modules/setup.local. When this landmark is found relative to VPATH relative to the executable, Python assumes it is running in a source tree and generates a different default sys.path. This code remains in release builds, so that release-ready builds can be built in-tree. On Windows, since builds are written to 'PCbuild/', the value of VPATH is set to '..\..', which results in a landmark of '..\..\Modules\setup.local'. This path is outside the install directory of Python, and may have different permissions, potentially allowing a low-privilege user to create the landmark and an alternative `Lib` folder that will be discovered by an otherwise restricted install. Such a setup occurs with the legacy default install location for all users (in the now superseded EXE installer), due to how Windows allows all users to create folders in the root directory of their OS drive. Our recommended mitigation on Windows is to migrate away from the legacy installer and use the new [Python install manager](https://www.python.org/downloads/latest/pymanager/) to install for the current user. Installs where the directory two levels above the Python installation directory have equivalent permissions are unaffected (in general, a per-user install cannot be modified at all by other users, removing any escalation of privilege risk, and could be directly modified by a privileged user, making the potential tampering irrelevant). Alternative mitigations might include preemptively creating and restricting access to a `Modules` directory. Be aware that only 3.13 and 3.14 will receive updated legacy installers - earlier fixes are only provided as sources. Platforms other than Windows allow VPATH to be overridden, but as they don't usually use a separated directory in the build for binaries, are unlikely to have a landmark reference outside of the install directory. The landmark detection involving VPATH is a fallback for when a more specific landmark - .\pybuilddir.txt - is absent, and was included for compatibility. Future releases of Python will no longer include the fallback, and so builds will need to generate or preserve the pybuilddir.txt file in order to work in-tree. This landmark file has been generated on Windows since 3.11, and on other platforms for longer.
CVE-2019-10160 WRITEUP CRITICAL WRITEUP
Python 2.7.0-2.7.16, 3.5, 3.6, 3.7, 3.8.0a4-3.8.0b1 - URL Parsing Security Regression
A security regression of CVE-2019-9636 was discovered in python since commit d537ab0ff9767ef024f26246899728f0116b1ec3 affecting versions 2.7, 3.5, 3.6, 3.7 and from v3.8.0a4 through v3.8.0b1, which still allows an attacker to exploit CVE-2019-9636 by abusing the user and password parts of a URL. When an application parses user-supplied URLs to store cookies, authentication credentials, or other kind of information, it is possible for an attacker to provide specially crafted URLs to make the application locate host-related information (e.g. cookies, authentication data) and send them to a different host than where it should, unlike if the URLs had been correctly parsed. The result of an attack may vary based on the application.
CVSS 9.8
CVE-2019-10160 WRITEUP CRITICAL WRITEUP
Python 2.7.0-2.7.16, 3.5, 3.6, 3.7, 3.8.0a4-3.8.0b1 - URL Parsing Security Regression
A security regression of CVE-2019-9636 was discovered in python since commit d537ab0ff9767ef024f26246899728f0116b1ec3 affecting versions 2.7, 3.5, 3.6, 3.7 and from v3.8.0a4 through v3.8.0b1, which still allows an attacker to exploit CVE-2019-9636 by abusing the user and password parts of a URL. When an application parses user-supplied URLs to store cookies, authentication credentials, or other kind of information, it is possible for an attacker to provide specially crafted URLs to make the application locate host-related information (e.g. cookies, authentication data) and send them to a different host than where it should, unlike if the URLs had been correctly parsed. The result of an attack may vary based on the application.
CVSS 9.8
CVE-2024-4030 WRITEUP HIGH WRITEUP
CPython < 3.8.20, 3.9.0-3.9.19, 3.10.0-3.10.14, 3.11.0-3.11.9, 3.12.0-3.12.3, 3.13.0a1 - Incorrect Default Permissions
On Windows a directory returned by tempfile.mkdtemp() would not always have permissions set to restrict reading and writing to the temporary directory by other users, instead usually inheriting the correct permissions from the default location. Alternate configurations or users without a profile directory may not have the intended permissions. If you’re not using Windows or haven’t changed the temporary directory location then you aren’t affected by this vulnerability. On other platforms the returned directory is consistently readable and writable only by the current user. This issue was caused by Python not supporting Unix permissions on Windows. The fix adds support for Unix “700” for the mkdir function on Windows which is used by mkdtemp() to ensure the newly created directory has the proper permissions.
CVSS 7.1
CVE-2019-10160 WRITEUP CRITICAL WRITEUP
Python 2.7.0-2.7.16, 3.5, 3.6, 3.7, 3.8.0a4-3.8.0b1 - URL Parsing Security Regression
A security regression of CVE-2019-9636 was discovered in python since commit d537ab0ff9767ef024f26246899728f0116b1ec3 affecting versions 2.7, 3.5, 3.6, 3.7 and from v3.8.0a4 through v3.8.0b1, which still allows an attacker to exploit CVE-2019-9636 by abusing the user and password parts of a URL. When an application parses user-supplied URLs to store cookies, authentication credentials, or other kind of information, it is possible for an attacker to provide specially crafted URLs to make the application locate host-related information (e.g. cookies, authentication data) and send them to a different host than where it should, unlike if the URLs had been correctly parsed. The result of an attack may vary based on the application.
CVSS 9.8
CVE-2024-4030 WRITEUP HIGH WRITEUP
CPython < 3.8.20, 3.9.0-3.9.19, 3.10.0-3.10.14, 3.11.0-3.11.9, 3.12.0-3.12.3, 3.13.0a1 - Incorrect Default Permissions
On Windows a directory returned by tempfile.mkdtemp() would not always have permissions set to restrict reading and writing to the temporary directory by other users, instead usually inheriting the correct permissions from the default location. Alternate configurations or users without a profile directory may not have the intended permissions. If you’re not using Windows or haven’t changed the temporary directory location then you aren’t affected by this vulnerability. On other platforms the returned directory is consistently readable and writable only by the current user. This issue was caused by Python not supporting Unix permissions on Windows. The fix adds support for Unix “700” for the mkdir function on Windows which is used by mkdtemp() to ensure the newly created directory has the proper permissions.
CVSS 7.1
CVE-2024-4030 WRITEUP HIGH WRITEUP
CPython < 3.8.20, 3.9.0-3.9.19, 3.10.0-3.10.14, 3.11.0-3.11.9, 3.12.0-3.12.3, 3.13.0a1 - Incorrect Default Permissions
On Windows a directory returned by tempfile.mkdtemp() would not always have permissions set to restrict reading and writing to the temporary directory by other users, instead usually inheriting the correct permissions from the default location. Alternate configurations or users without a profile directory may not have the intended permissions. If you’re not using Windows or haven’t changed the temporary directory location then you aren’t affected by this vulnerability. On other platforms the returned directory is consistently readable and writable only by the current user. This issue was caused by Python not supporting Unix permissions on Windows. The fix adds support for Unix “700” for the mkdir function on Windows which is used by mkdtemp() to ensure the newly created directory has the proper permissions.
CVSS 7.1
CVE-2024-4030 WRITEUP HIGH WRITEUP
CPython < 3.8.20, 3.9.0-3.9.19, 3.10.0-3.10.14, 3.11.0-3.11.9, 3.12.0-3.12.3, 3.13.0a1 - Incorrect Default Permissions
On Windows a directory returned by tempfile.mkdtemp() would not always have permissions set to restrict reading and writing to the temporary directory by other users, instead usually inheriting the correct permissions from the default location. Alternate configurations or users without a profile directory may not have the intended permissions. If you’re not using Windows or haven’t changed the temporary directory location then you aren’t affected by this vulnerability. On other platforms the returned directory is consistently readable and writable only by the current user. This issue was caused by Python not supporting Unix permissions on Windows. The fix adds support for Unix “700” for the mkdir function on Windows which is used by mkdtemp() to ensure the newly created directory has the proper permissions.
CVSS 7.1
CVE-2024-4030 WRITEUP HIGH WRITEUP
CPython < 3.8.20, 3.9.0-3.9.19, 3.10.0-3.10.14, 3.11.0-3.11.9, 3.12.0-3.12.3, 3.13.0a1 - Incorrect Default Permissions
On Windows a directory returned by tempfile.mkdtemp() would not always have permissions set to restrict reading and writing to the temporary directory by other users, instead usually inheriting the correct permissions from the default location. Alternate configurations or users without a profile directory may not have the intended permissions. If you’re not using Windows or haven’t changed the temporary directory location then you aren’t affected by this vulnerability. On other platforms the returned directory is consistently readable and writable only by the current user. This issue was caused by Python not supporting Unix permissions on Windows. The fix adds support for Unix “700” for the mkdir function on Windows which is used by mkdtemp() to ensure the newly created directory has the proper permissions.
CVSS 7.1
CVE-2024-4030 WRITEUP HIGH WRITEUP
CPython < 3.8.20, 3.9.0-3.9.19, 3.10.0-3.10.14, 3.11.0-3.11.9, 3.12.0-3.12.3, 3.13.0a1 - Incorrect Default Permissions
On Windows a directory returned by tempfile.mkdtemp() would not always have permissions set to restrict reading and writing to the temporary directory by other users, instead usually inheriting the correct permissions from the default location. Alternate configurations or users without a profile directory may not have the intended permissions. If you’re not using Windows or haven’t changed the temporary directory location then you aren’t affected by this vulnerability. On other platforms the returned directory is consistently readable and writable only by the current user. This issue was caused by Python not supporting Unix permissions on Windows. The fix adds support for Unix “700” for the mkdir function on Windows which is used by mkdtemp() to ensure the newly created directory has the proper permissions.
CVSS 7.1
CVE-2024-4030 WRITEUP HIGH WRITEUP
CPython < 3.8.20, 3.9.0-3.9.19, 3.10.0-3.10.14, 3.11.0-3.11.9, 3.12.0-3.12.3, 3.13.0a1 - Incorrect Default Permissions
On Windows a directory returned by tempfile.mkdtemp() would not always have permissions set to restrict reading and writing to the temporary directory by other users, instead usually inheriting the correct permissions from the default location. Alternate configurations or users without a profile directory may not have the intended permissions. If you’re not using Windows or haven’t changed the temporary directory location then you aren’t affected by this vulnerability. On other platforms the returned directory is consistently readable and writable only by the current user. This issue was caused by Python not supporting Unix permissions on Windows. The fix adds support for Unix “700” for the mkdir function on Windows which is used by mkdtemp() to ensure the newly created directory has the proper permissions.
CVSS 7.1
CVE-2024-4030 WRITEUP HIGH WRITEUP
CPython < 3.8.20, 3.9.0-3.9.19, 3.10.0-3.10.14, 3.11.0-3.11.9, 3.12.0-3.12.3, 3.13.0a1 - Incorrect Default Permissions
On Windows a directory returned by tempfile.mkdtemp() would not always have permissions set to restrict reading and writing to the temporary directory by other users, instead usually inheriting the correct permissions from the default location. Alternate configurations or users without a profile directory may not have the intended permissions. If you’re not using Windows or haven’t changed the temporary directory location then you aren’t affected by this vulnerability. On other platforms the returned directory is consistently readable and writable only by the current user. This issue was caused by Python not supporting Unix permissions on Windows. The fix adds support for Unix “700” for the mkdir function on Windows which is used by mkdtemp() to ensure the newly created directory has the proper permissions.
CVSS 7.1
CVE-2024-4030 WRITEUP HIGH WRITEUP
CPython < 3.8.20, 3.9.0-3.9.19, 3.10.0-3.10.14, 3.11.0-3.11.9, 3.12.0-3.12.3, 3.13.0a1 - Incorrect Default Permissions
On Windows a directory returned by tempfile.mkdtemp() would not always have permissions set to restrict reading and writing to the temporary directory by other users, instead usually inheriting the correct permissions from the default location. Alternate configurations or users without a profile directory may not have the intended permissions. If you’re not using Windows or haven’t changed the temporary directory location then you aren’t affected by this vulnerability. On other platforms the returned directory is consistently readable and writable only by the current user. This issue was caused by Python not supporting Unix permissions on Windows. The fix adds support for Unix “700” for the mkdir function on Windows which is used by mkdtemp() to ensure the newly created directory has the proper permissions.
CVSS 7.1
CVE-2024-4030 WRITEUP HIGH WRITEUP
CPython < 3.8.20, 3.9.0-3.9.19, 3.10.0-3.10.14, 3.11.0-3.11.9, 3.12.0-3.12.3, 3.13.0a1 - Incorrect Default Permissions
On Windows a directory returned by tempfile.mkdtemp() would not always have permissions set to restrict reading and writing to the temporary directory by other users, instead usually inheriting the correct permissions from the default location. Alternate configurations or users without a profile directory may not have the intended permissions. If you’re not using Windows or haven’t changed the temporary directory location then you aren’t affected by this vulnerability. On other platforms the returned directory is consistently readable and writable only by the current user. This issue was caused by Python not supporting Unix permissions on Windows. The fix adds support for Unix “700” for the mkdir function on Windows which is used by mkdtemp() to ensure the newly created directory has the proper permissions.
CVSS 7.1
CVE-2024-4030 WRITEUP HIGH WRITEUP
CPython < 3.8.20, 3.9.0-3.9.19, 3.10.0-3.10.14, 3.11.0-3.11.9, 3.12.0-3.12.3, 3.13.0a1 - Incorrect Default Permissions
On Windows a directory returned by tempfile.mkdtemp() would not always have permissions set to restrict reading and writing to the temporary directory by other users, instead usually inheriting the correct permissions from the default location. Alternate configurations or users without a profile directory may not have the intended permissions. If you’re not using Windows or haven’t changed the temporary directory location then you aren’t affected by this vulnerability. On other platforms the returned directory is consistently readable and writable only by the current user. This issue was caused by Python not supporting Unix permissions on Windows. The fix adds support for Unix “700” for the mkdir function on Windows which is used by mkdtemp() to ensure the newly created directory has the proper permissions.
CVSS 7.1
CVE-2026-2297 WRITEUP MEDIUM WRITEUP
CPython < 3.15.0a7 - Unprotected User Data Exposure via SourcelessFileLoader Import Hook
The import hook in CPython that handles legacy *.pyc files (SourcelessFileLoader) is incorrectly handled in FileLoader (a base class) and so does not use io.open_code() to read the .pyc files. sys.audit handlers for this audit event therefore do not fire.
CVE-2026-2297 WRITEUP MEDIUM WRITEUP
CPython < 3.15.0a7 - Unprotected User Data Exposure via SourcelessFileLoader Import Hook
The import hook in CPython that handles legacy *.pyc files (SourcelessFileLoader) is incorrectly handled in FileLoader (a base class) and so does not use io.open_code() to read the .pyc files. sys.audit handlers for this audit event therefore do not fire.
CVE-2026-2297 WRITEUP MEDIUM WRITEUP
CPython < 3.15.0a7 - Unprotected User Data Exposure via SourcelessFileLoader Import Hook
The import hook in CPython that handles legacy *.pyc files (SourcelessFileLoader) is incorrectly handled in FileLoader (a base class) and so does not use io.open_code() to read the .pyc files. sys.audit handlers for this audit event therefore do not fire.
CVE-2026-2297 WRITEUP MEDIUM WRITEUP
CPython < 3.15.0a7 - Unprotected User Data Exposure via SourcelessFileLoader Import Hook
The import hook in CPython that handles legacy *.pyc files (SourcelessFileLoader) is incorrectly handled in FileLoader (a base class) and so does not use io.open_code() to read the .pyc files. sys.audit handlers for this audit event therefore do not fire.
CVE-2026-2297 WRITEUP MEDIUM WRITEUP
CPython < 3.15.0a7 - Unprotected User Data Exposure via SourcelessFileLoader Import Hook
The import hook in CPython that handles legacy *.pyc files (SourcelessFileLoader) is incorrectly handled in FileLoader (a base class) and so does not use io.open_code() to read the .pyc files. sys.audit handlers for this audit event therefore do not fire.