CVE-2021-31535

CRITICAL

X.org Libx11 < 1.7.1 - Buffer Overflow

Title source: rule
STIX 2.1

Description

LookupCol.c in X.Org X through X11R7.7 and libX11 before 1.7.1 might allow remote attackers to execute arbitrary code. The libX11 XLookupColor request (intended for server-side color lookup) contains a flaw allowing a client to send color-name requests with a name longer than the maximum size allowed by the protocol (and also longer than the maximum packet size for normal-sized packets). The user-controlled data exceeding the maximum size is then interpreted by the server as additional X protocol requests and executed, e.g., to disable X server authorization completely. For example, if the victim encounters malicious terminal control sequences for color codes, then the attacker may be able to take full control of the running graphical session.

References (19)

Core 19
Core References
Exploit, Third Party Advisory x_refsource_misc
https://unparalleled.eu/publications/2021/advisory-unpar-2021-1.txt
Third Party Advisory x_refsource_misc
https://lists.freedesktop.org/archives/xorg/
Mailing List, Third Party Advisory mailing-list x_refsource_mlist
http://www.openwall.com/lists/oss-security/2021/05/18/2
Mailing List, Third Party Advisory mailing-list x_refsource_fulldisc
http://seclists.org/fulldisclosure/2021/May/52
Third Party Advisory mailing-list x_refsource_mlist
https://lists.debian.org/debian-lts-announce/2021/05/msg00021.html
Third Party Advisory vendor-advisory x_refsource_debian
https://www.debian.org/security/2021/dsa-4920
Third Party Advisory vendor-advisory x_refsource_gentoo
https://security.gentoo.org/glsa/202105-16
Mailing List, Third Party Advisory x_refsource_misc
https://www.openwall.com/lists/oss-security/2021/05/18/3
Mailing List, Third Party Advisory x_refsource_misc
https://www.openwall.com/lists/oss-security/2021/05/18/2
Third Party Advisory x_refsource_confirm
https://security.netapp.com/advisory/ntap-20210813-0001/

Scores

CVSS v3 9.8
EPSS 0.0206
EPSS Percentile 84.0%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Details

CWE
CWE-120
Status published
Products (3)
fedoraproject/fedora 33
x.org/libx11 < 1.7.1
x.org/x_window_system < x11r7.7
Published May 27, 2021
Tracked Since Feb 18, 2026