Jakub Witczak

24 exploits Active since Feb 2025
CVE-2026-59251 WRITEUP HIGH WRITEUP
Denial of service via exponential certificate policy tree growth in path validation
Allocation of resources without limits in Erlang/OTP public_key certificate path validation allows a remote unauthenticated attacker to cause denial of service by sending a crafted X.509 certificate chain during the TLS handshake. During RFC 5280 policy processing in public_key:pkix_path_validation/3, the certificate policy tree maintained by pubkey_policy_tree grows without an upper bound. When a certificate chain contains M policies per certificate and K certificates, the tree grows on the order of M^K nodes because pubkey_policy_tree:add_leaves/2 and pubkey_policy_tree:add_leaf_siblings/2 extend the tree per policy per certificate. A modest chain with many policies per certificate is enough to pin BEAM schedulers and exhaust the node's memory, taking down the entire VM. The attacker only needs to be able to present a certificate chain to the victim, which is the normal precondition for a TLS handshake, so exploitation succeeds against any incoming or outgoing TLS connection that validates the peer's chain (the default for SSL/TLS clients and mutual-TLS servers). This is the same vulnerability class as OpenSSL's X509_verify_cert policy tree DoS. This vulnerability is associated with program files lib/public_key/src/pubkey_policy_tree.erl and program routines pubkey_policy_tree:add_leaves/2 and pubkey_policy_tree:add_leaf_siblings/2. This issue affects OTP from OTP 26.2 before OTP 29.0.4, OTP 28.5.0.4 and OTP 27.3.4.15, corresponding to public_key from 1.15 before 1.21.4, 1.20.3.4 and 1.17.1.5.
CVE-2026-59250 WRITEUP HIGH WRITEUP
Megaco flex scanner buffer overflow via oversized property parm name
Classic buffer overflow in the Erlang/OTP megaco flex scanner C driver allows a remote unauthenticated attacker to corrupt the driver's memory (and potentially achieve remote code execution or a denial-of-service crash) by sending a single text-encoded H.248/Megaco message containing an oversized property parm name. When tokenizing a Local/Remote descriptor, mfs_load_property_groups extracts the attacker-controlled property name (bounded only by the message length) and, when no value follows, formats it into a fixed 512-byte error_msg field of the MfsErlDrvData struct using an unchecked sprintf call. Names longer than roughly 452 bytes overflow into the immediately following struct fields (text_buf, text_ptr, term_spec, term_spec_size, term_spec_index), overwriting live pointers and counters with attacker-chosen bytes. Subsequent scanner code writes and frees through the corrupted pointers, producing arbitrary write and arbitrary free primitives inside the BEAM VM process, which can be leveraged for remote code execution. On builds compiled with _FORTIFY_SOURCE the overflow is detected at runtime and terminates the process with SIGABRT, resulting in denial of service. The overflow occurs in the flex scanner before any grammar or Megaco-level authentication processing, so exploitation requires only network reachability to the megaco transport port on a node configured with {scanner, flex}. This vulnerability is associated with program files lib/megaco/src/flex/megaco_flex_scanner_drv.flex.src and program routines mfs_load_property_groups. This issue affects OTP from OTP 17.0 before OTP 29.0.4, OTP 28.5.0.4 and OTP 27.3.4.15, corresponding to megaco from 3.17.1 before 4.9.1, 4.8.3.1 and 4.7.2.2. Versions prior to OTP 17.0 are also affected but are not listed because the OTP version scheme is only defined from OTP 17.0 onwards.
CVE-2026-59251 WRITEUP HIGH WRITEUP
Denial of service via exponential certificate policy tree growth in path validation
Allocation of resources without limits in Erlang/OTP public_key certificate path validation allows a remote unauthenticated attacker to cause denial of service by sending a crafted X.509 certificate chain during the TLS handshake. During RFC 5280 policy processing in public_key:pkix_path_validation/3, the certificate policy tree maintained by pubkey_policy_tree grows without an upper bound. When a certificate chain contains M policies per certificate and K certificates, the tree grows on the order of M^K nodes because pubkey_policy_tree:add_leaves/2 and pubkey_policy_tree:add_leaf_siblings/2 extend the tree per policy per certificate. A modest chain with many policies per certificate is enough to pin BEAM schedulers and exhaust the node's memory, taking down the entire VM. The attacker only needs to be able to present a certificate chain to the victim, which is the normal precondition for a TLS handshake, so exploitation succeeds against any incoming or outgoing TLS connection that validates the peer's chain (the default for SSL/TLS clients and mutual-TLS servers). This is the same vulnerability class as OpenSSL's X509_verify_cert policy tree DoS. This vulnerability is associated with program files lib/public_key/src/pubkey_policy_tree.erl and program routines pubkey_policy_tree:add_leaves/2 and pubkey_policy_tree:add_leaf_siblings/2. This issue affects OTP from OTP 26.2 before OTP 29.0.4, OTP 28.5.0.4 and OTP 27.3.4.15, corresponding to public_key from 1.15 before 1.21.4, 1.20.3.4 and 1.17.1.5.
CVE-2026-48859 WRITEUP MEDIUM WRITEUP
SSH server timing side-channel in ssh_auth:check_password/3 allows unauthenticated username enumeration
Observable Timing Discrepancy vulnerability in Erlang/OTP ssh (ssh_auth, ssh_options modules) allows unauthenticated remote username enumeration via timing side-channel in password authentication. When the SSH daemon is configured with the user_passwords or password option, ssh_auth:check_password/3 performs a PBKDF2-SHA256 computation with 600,000 iterations (~300ms) for valid usernames, but returns immediately (~0ms) for invalid usernames via the ssh_options:get_password_option/2 path. This timing difference is detectable in a single authentication attempt and allows an unauthenticated attacker to distinguish valid from invalid usernames. The user_passwords and password options are documented as intended for test purposes; the recommended alternative is pwdfun, which is not affected by this vulnerability. This vulnerability is associated with program files lib/ssh/src/ssh_auth.erl and lib/ssh/src/ssh_options.erl. This issue affects OTP from OTP 29.0 before OTP 29.0.2, corresponding to ssh from 6.0 before 6.0.1.
CVSS 5.3
CVE-2026-42791 WRITEUP LOW WRITEUP
OCSP responder certificate validity period not checked in public_key
Improper Certificate Validation vulnerability in Erlang OTP public_key (pubkey_ocsp module) allows forged OCSP responses signed with an expired responder certificate to be accepted as valid. OCSP response verification in pubkey_ocsp:verify_response/5 and pubkey_ocsp:is_authorized_responder/3 in lib/public_key/src/pubkey_ocsp.erl does not check the validity period (notBefore/notAfter) of the OCSP responder certificate. An attacker who has obtained the private key of an expired CA-designated OCSP responder certificate can forge OCSP responses that Erlang/OTP accepts as valid. This affects TLS clients using OCSP stapling via the ssl application: a malicious or compromised server can present a revoked TLS certificate together with a forged OCSP response signed by an expired responder key, and the client will accept the revoked certificate as valid. It also affects applications calling public_key:pkix_ocsp_validate/5 directly, where the impact depends on the use case — server-side client certificate validation using this API may allow authentication bypass with a revoked client certificate. This issue affects OTP from OTP 27.0 before OTP 29.0.1, OTP 28.5.0.1 and OTP 27.3.4.12, corresponding to public_key from 1.16 before 1.21.1, 1.20.3.1 and 1.17.1.3.
CVSS 3.7
CVE-2026-42791 WRITEUP LOW WRITEUP
OCSP responder certificate validity period not checked in public_key
Improper Certificate Validation vulnerability in Erlang OTP public_key (pubkey_ocsp module) allows forged OCSP responses signed with an expired responder certificate to be accepted as valid. OCSP response verification in pubkey_ocsp:verify_response/5 and pubkey_ocsp:is_authorized_responder/3 in lib/public_key/src/pubkey_ocsp.erl does not check the validity period (notBefore/notAfter) of the OCSP responder certificate. An attacker who has obtained the private key of an expired CA-designated OCSP responder certificate can forge OCSP responses that Erlang/OTP accepts as valid. This affects TLS clients using OCSP stapling via the ssl application: a malicious or compromised server can present a revoked TLS certificate together with a forged OCSP response signed by an expired responder key, and the client will accept the revoked certificate as valid. It also affects applications calling public_key:pkix_ocsp_validate/5 directly, where the impact depends on the use case — server-side client certificate validation using this API may allow authentication bypass with a revoked client certificate. This issue affects OTP from OTP 27.0 before OTP 29.0.1, OTP 28.5.0.1 and OTP 27.3.4.12, corresponding to public_key from 1.16 before 1.21.1, 1.20.3.1 and 1.17.1.3.
CVSS 3.7
CVE-2025-32433 WRITEUP CRITICAL WRITEUP
Erlang OTP Pre-Auth RCE Scanner and Exploit
Erlang/OTP is a set of libraries for the Erlang programming language. Prior to versions OTP-27.3.3, OTP-26.2.5.11, and OTP-25.3.2.20, a SSH server may allow an attacker to perform unauthenticated remote code execution (RCE). By exploiting a flaw in SSH protocol message handling, a malicious actor could gain unauthorized access to affected systems and execute arbitrary commands without valid credentials. This issue is patched in versions OTP-27.3.3, OTP-26.2.5.11, and OTP-25.3.2.20. A temporary workaround involves disabling the SSH server or to prevent access via firewall rules.
CVSS 10.0
CVE-2025-32433 WRITEUP CRITICAL WRITEUP
Erlang OTP Pre-Auth RCE Scanner and Exploit
Erlang/OTP is a set of libraries for the Erlang programming language. Prior to versions OTP-27.3.3, OTP-26.2.5.11, and OTP-25.3.2.20, a SSH server may allow an attacker to perform unauthenticated remote code execution (RCE). By exploiting a flaw in SSH protocol message handling, a malicious actor could gain unauthorized access to affected systems and execute arbitrary commands without valid credentials. This issue is patched in versions OTP-27.3.3, OTP-26.2.5.11, and OTP-25.3.2.20. A temporary workaround involves disabling the SSH server or to prevent access via firewall rules.
CVSS 10.0
CVE-2025-32433 WRITEUP CRITICAL WRITEUP
Erlang OTP Pre-Auth RCE Scanner and Exploit
Erlang/OTP is a set of libraries for the Erlang programming language. Prior to versions OTP-27.3.3, OTP-26.2.5.11, and OTP-25.3.2.20, a SSH server may allow an attacker to perform unauthenticated remote code execution (RCE). By exploiting a flaw in SSH protocol message handling, a malicious actor could gain unauthorized access to affected systems and execute arbitrary commands without valid credentials. This issue is patched in versions OTP-27.3.3, OTP-26.2.5.11, and OTP-25.3.2.20. A temporary workaround involves disabling the SSH server or to prevent access via firewall rules.
CVSS 10.0
CVE-2025-48038 WRITEUP MEDIUM WRITEUP
Erlang OTP - Resource Leak Exposure
Allocation of Resources Without Limits or Throttling vulnerability in Erlang OTP ssh (ssh_sftp modules) allows Excessive Allocation, Resource Leak Exposure. This vulnerability is associated with program files lib/ssh/src/ssh_sftpd.erl. This issue affects OTP from OTP 17.0 before OTP 28.0.3, OTP 27.3.4.3 and OTP 26.2.5.15, corresponding to ssh from 3.0.1 before 5.3.3, 5.2.11.3 and 5.1.4.12.
CVE-2025-48039 WRITEUP MEDIUM WRITEUP
Erlang OTP <28.0.3 - Excessive Allocation
Allocation of Resources Without Limits or Throttling vulnerability in Erlang OTP ssh (ssh_sftp modules) allows Excessive Allocation, Resource Leak Exposure. This vulnerability is associated with program files lib/ssh/src/ssh_sftpd.erl. This issue affects OTP from OTP 17.0 before OTP 28.0.3, OTP 27.3.4.3 and OTP 26.2.5.15, corresponding to ssh from 3.0.1 before 5.3.3, 5.2.11.3 and 5.1.4.12.
CVE-2025-48040 WRITEUP MEDIUM WRITEUP
Erlang OTP <28.0.3 - Uncontrolled Resource Consumption
Uncontrolled Resource Consumption vulnerability in Erlang OTP ssh (ssh_sftp modules) allows Excessive Allocation, Flooding. This vulnerability is associated with program files lib/ssh/src/ssh_sftpd.erl. This issue affects OTP from OTP 17.0 before OTP 28.0.3, OTP 27.3.4.3 and OTP 26.2.5.15, corresponding to ssh from 3.0.1 before 5.3.3, 5.2.11.3 and 5.1.4.12.
CVE-2025-48041 WRITEUP HIGH WRITEUP
Erlang/OTP 17.0-28.0.3, 27.3.4.3, 26.2.5.15 - Uncontrolled Resource Consumption in SSH SFTP Module
Allocation of Resources Without Limits or Throttling vulnerability in Erlang OTP ssh (ssh_sftp modules) allows Excessive Allocation, Flooding. This vulnerability is associated with program files lib/ssh/src/ssh_sftpd.erl. This issue affects OTP from OTP 17.0 before OTP 28.0.3, OTP 27.3.4.3 and OTP 26.2.5.15, corresponding to ssh from 3.0.1 before 5.3.3, 5.2.11.3 and 5.1.4.12.
CVE-2026-23942 WRITEUP MEDIUM WRITEUP
Erlang OTP ssh_sftpd - Path Traversal
Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') vulnerability in Erlang OTP (ssh_sftpd module) allows Path Traversal. This vulnerability is associated with program files lib/ssh/src/ssh_sftpd.erl and program routines ssh_sftpd:is_within_root/2. The SFTP server uses string prefix matching via lists:prefix/2 rather than proper path component validation when checking if a path is within the configured root directory. This allows authenticated users to access sibling directories that share a common name prefix with the configured root directory. For example, if root is set to /home/user1, paths like /home/user10 or /home/user1_backup would incorrectly be considered within the root. This issue affects OTP from OTP 17.0 before OTP 28.4.1, OTP 27.3.4.9 and OTP 26.2.5.18, corresponding to ssh from 3.0.1 before 5.5.1, 5.2.11.6 and 5.1.4.14.
CVSS 5.4
CVE-2026-23942 WRITEUP MEDIUM WRITEUP
Erlang OTP ssh_sftpd - Path Traversal
Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') vulnerability in Erlang OTP (ssh_sftpd module) allows Path Traversal. This vulnerability is associated with program files lib/ssh/src/ssh_sftpd.erl and program routines ssh_sftpd:is_within_root/2. The SFTP server uses string prefix matching via lists:prefix/2 rather than proper path component validation when checking if a path is within the configured root directory. This allows authenticated users to access sibling directories that share a common name prefix with the configured root directory. For example, if root is set to /home/user1, paths like /home/user10 or /home/user1_backup would incorrectly be considered within the root. This issue affects OTP from OTP 17.0 before OTP 28.4.1, OTP 27.3.4.9 and OTP 26.2.5.18, corresponding to ssh from 3.0.1 before 5.5.1, 5.2.11.6 and 5.1.4.14.
CVSS 5.4
CVE-2026-32144 WRITEUP HIGH WRITEUP
OCSP designated-responder authorization bypass via missing signature verification
Improper Certificate Validation vulnerability in Erlang OTP public_key (pubkey_ocsp module) allows OCSP designated-responder authorization bypass via missing signature verification. The OCSP response validation in public_key:pkix_ocsp_validate/5 does not verify that a CA-designated responder certificate was cryptographically signed by the issuing CA. Instead, it only checks that the responder certificate's issuer name matches the CA's subject name and that the certificate has the OCSPSigning extended key usage. An attacker who can intercept or control OCSP responses can create a self-signed certificate with a matching issuer name and the OCSPSigning EKU, and use it to forge OCSP responses that mark revoked certificates as valid. This affects SSL/TLS clients using OCSP stapling, which may accept connections to servers with revoked certificates, potentially transmitting sensitive data to compromised servers. Applications using the public_key:pkix_ocsp_validate/5 API directly are also affected, with impact depending on usage context. This vulnerability is associated with program files lib/public_key/src/pubkey_ocsp.erl and program routines pubkey_ocsp:is_authorized_responder/3. This issue affects OTP from OTP 27.0 before OTP 28.4.2 and OTP 27.3.4.10, corresponding to public_key from 1.16 before 1.20.3 and 1.17.1.2, and ssl from 11.2 before 11.5.4 and 11.2.12.7.
CVSS 7.4
CVE-2026-32144 WRITEUP HIGH WRITEUP
OCSP designated-responder authorization bypass via missing signature verification
Improper Certificate Validation vulnerability in Erlang OTP public_key (pubkey_ocsp module) allows OCSP designated-responder authorization bypass via missing signature verification. The OCSP response validation in public_key:pkix_ocsp_validate/5 does not verify that a CA-designated responder certificate was cryptographically signed by the issuing CA. Instead, it only checks that the responder certificate's issuer name matches the CA's subject name and that the certificate has the OCSPSigning extended key usage. An attacker who can intercept or control OCSP responses can create a self-signed certificate with a matching issuer name and the OCSPSigning EKU, and use it to forge OCSP responses that mark revoked certificates as valid. This affects SSL/TLS clients using OCSP stapling, which may accept connections to servers with revoked certificates, potentially transmitting sensitive data to compromised servers. Applications using the public_key:pkix_ocsp_validate/5 API directly are also affected, with impact depending on usage context. This vulnerability is associated with program files lib/public_key/src/pubkey_ocsp.erl and program routines pubkey_ocsp:is_authorized_responder/3. This issue affects OTP from OTP 27.0 before OTP 28.4.2 and OTP 27.3.4.10, corresponding to public_key from 1.16 before 1.20.3 and 1.17.1.2, and ssl from 11.2 before 11.5.4 and 11.2.12.7.
CVSS 7.4
CVE-2026-23942 WRITEUP MEDIUM WRITEUP
Erlang OTP ssh_sftpd - Path Traversal
Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') vulnerability in Erlang OTP (ssh_sftpd module) allows Path Traversal. This vulnerability is associated with program files lib/ssh/src/ssh_sftpd.erl and program routines ssh_sftpd:is_within_root/2. The SFTP server uses string prefix matching via lists:prefix/2 rather than proper path component validation when checking if a path is within the configured root directory. This allows authenticated users to access sibling directories that share a common name prefix with the configured root directory. For example, if root is set to /home/user1, paths like /home/user10 or /home/user1_backup would incorrectly be considered within the root. This issue affects OTP from OTP 17.0 before OTP 28.4.1, OTP 27.3.4.9 and OTP 26.2.5.18, corresponding to ssh from 3.0.1 before 5.5.1, 5.2.11.6 and 5.1.4.14.
CVSS 5.4
CVE-2025-26618 WRITEUP HIGH WRITEUP
Erlang/OTP 25.3.2.18-27.2.3 - Authenticated Denial of Service via SFTP Packet Size Mismatch
Erlang is a programming language and runtime system for building massively scalable soft real-time systems with requirements on high availability. OTP is a set of Erlang libraries, which consists of the Erlang runtime system, a number of ready-to-use components mainly written in Erlang. Packet size is not verified properly for SFTP packets. As a result when multiple SSH packets (conforming to max SSH packet size) are received by ssh, they might be combined into an SFTP packet which will exceed the max allowed packet size and potentially cause large amount of memory to be allocated. Note that situation described above can only happen for successfully authenticated users after completing the SSH handshake. This issue has been patched in OTP versions 27.2.4, 26.2.5.9, and 25.3.2.18. There are no known workarounds for this vulnerability.
CVE-2025-46712 WRITEUP LOW WRITEUP
Erlang/OTP <27.3.4, <26.2.5.12, <25.3.2.21 - Man-in-the-Middle
Erlang/OTP is a set of libraries for the Erlang programming language. In versions prior to OTP-27.3.4 (for OTP-27), OTP-26.2.5.12 (for OTP-26), and OTP-25.3.2.21 (for OTP-25), Erlang/OTP SSH fails to enforce strict KEX handshake hardening measures by allowing optional messages to be exchanged. This allows a Man-in-the-Middle attacker to inject these messages in a connection during the handshake. This issue has been patched in versions OTP-27.3.4 (for OTP-27), OTP-26.2.5.12 (for OTP-26), and OTP-25.3.2.21 (for OTP-25).
CVSS 3.7
CVE-2025-48038 WRITEUP MEDIUM WRITEUP
Erlang OTP - Resource Leak Exposure
Allocation of Resources Without Limits or Throttling vulnerability in Erlang OTP ssh (ssh_sftp modules) allows Excessive Allocation, Resource Leak Exposure. This vulnerability is associated with program files lib/ssh/src/ssh_sftpd.erl. This issue affects OTP from OTP 17.0 before OTP 28.0.3, OTP 27.3.4.3 and OTP 26.2.5.15, corresponding to ssh from 3.0.1 before 5.3.3, 5.2.11.3 and 5.1.4.12.
CVE-2025-48039 WRITEUP MEDIUM WRITEUP
Erlang OTP <28.0.3 - Excessive Allocation
Allocation of Resources Without Limits or Throttling vulnerability in Erlang OTP ssh (ssh_sftp modules) allows Excessive Allocation, Resource Leak Exposure. This vulnerability is associated with program files lib/ssh/src/ssh_sftpd.erl. This issue affects OTP from OTP 17.0 before OTP 28.0.3, OTP 27.3.4.3 and OTP 26.2.5.15, corresponding to ssh from 3.0.1 before 5.3.3, 5.2.11.3 and 5.1.4.12.
CVE-2025-48040 WRITEUP MEDIUM WRITEUP
Erlang OTP <28.0.3 - Uncontrolled Resource Consumption
Uncontrolled Resource Consumption vulnerability in Erlang OTP ssh (ssh_sftp modules) allows Excessive Allocation, Flooding. This vulnerability is associated with program files lib/ssh/src/ssh_sftpd.erl. This issue affects OTP from OTP 17.0 before OTP 28.0.3, OTP 27.3.4.3 and OTP 26.2.5.15, corresponding to ssh from 3.0.1 before 5.3.3, 5.2.11.3 and 5.1.4.12.
CVE-2025-48041 WRITEUP HIGH WRITEUP
Erlang/OTP 17.0-28.0.3, 27.3.4.3, 26.2.5.15 - Uncontrolled Resource Consumption in SSH SFTP Module
Allocation of Resources Without Limits or Throttling vulnerability in Erlang OTP ssh (ssh_sftp modules) allows Excessive Allocation, Flooding. This vulnerability is associated with program files lib/ssh/src/ssh_sftpd.erl. This issue affects OTP from OTP 17.0 before OTP 28.0.3, OTP 27.3.4.3 and OTP 26.2.5.15, corresponding to ssh from 3.0.1 before 5.3.3, 5.2.11.3 and 5.1.4.12.