critical
CVE-2021-31535
libX11: missing request length checks
In the Trivy database since at least 24 Oct 2026, 07:11 UTCWhen it arrived before that build is not recorded.
Severity by source
NVD9.8CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Red Hat8.1CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Julia9.8CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Trivy's own label is CRITICAL. Rated critical by NVD, Julia. Rated lower by Red Hat (high), Amazon (high), AlmaLinux (medium), Oracle (medium), Rocky Linux (medium), Ubuntu (medium).
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.
Affected packages and fixed versions
| Source | Package | Fixed in |
|---|---|---|
| julia::Julia Ecosystem Security Advisories | Xorg_libX11_jll | 1.8.6+0 |
| alma 8 | libX11, libX11-common, libX11-devel and 1 more | 1.6.8-5.el8 |
| alpine 3.10 | libx11 | 1.6.12-r1 |
| alpine 3.11 | libx11 | 1.6.12-r1 |
| alpine 3.12 | libx11 | 1.6.12-r1 |
| alpine 3.13 | libx11 | 1.7.1-r0 |
| alpine 3.14 | libx11 | 1.7.1-r0 |
| alpine 3.15 | libx11 | 1.7.1-r0 |
| alpine 3.16 | libx11 | 1.7.1-r0 |
| alpine 3.17 | libx11 | 1.7.1-r0 |
| alpine 3.18 | libx11 | 1.7.1-r0 |
| alpine 3.19 | libx11 | 1.7.1-r0 |
Show all 60 entries from 41 sources
| Source | Package | Fixed in |
|---|---|---|
| julia::Julia Ecosystem Security Advisories | Xorg_libX11_jll | 1.8.6+0 |
| alma 8 | libX11 | 1.6.8-5.el8 |
| alma 8 | libX11-common | 1.6.8-5.el8 |
| alma 8 | libX11-devel | 1.6.8-5.el8 |
| alma 8 | libX11-xcb | 1.6.8-5.el8 |
| alpine 3.10 | libx11 | 1.6.12-r1 |
| alpine 3.11 | libx11 | 1.6.12-r1 |
| alpine 3.12 | libx11 | 1.6.12-r1 |
| alpine 3.13 | libx11 | 1.7.1-r0 |
| alpine 3.14 | libx11 | 1.7.1-r0 |
| alpine 3.15 | libx11 | 1.7.1-r0 |
| alpine 3.16 | libx11 | 1.7.1-r0 |
| alpine 3.17 | libx11 | 1.7.1-r0 |
| alpine 3.18 | libx11 | 1.7.1-r0 |
| alpine 3.19 | libx11 | 1.7.1-r0 |
| alpine 3.20 | libx11 | 1.7.1-r0 |
| alpine 3.21 | libx11 | 1.7.1-r0 |
| alpine 3.22 | libx11 | 1.7.1-r0 |
| alpine 3.23 | libx11 | 1.7.1-r0 |
| alpine 3.24 | libx11 | 1.7.1-r0 |
| alpine edge | libx11 | 1.7.1-r0 |
| amazon linux 1 | libX11 | 1.6.0-2.2.14.amzn1 |
| amazon linux 1 | libX11-common | 1.6.0-2.2.14.amzn1 |
| amazon linux 1 | libX11-debuginfo | 1.6.0-2.2.14.amzn1 |
| amazon linux 1 | libX11-devel | 1.6.0-2.2.14.amzn1 |
| amazon linux 2 | libX11 | 1.6.7-3.amzn2.0.2 |
| amazon linux 2 | libX11-common | 1.6.7-3.amzn2.0.2 |
| amazon linux 2 | libX11-debuginfo | 1.6.7-3.amzn2.0.2 |
| amazon linux 2 | libX11-devel | 1.6.7-3.amzn2.0.2 |
| debian 10 | libx11 | 2:1.6.7-1+deb10u2 |
| debian 11 | libx11 | 2:1.7.1-1 |
| debian 12 | libx11 | 2:1.7.1-1 |
| debian 13 | libx11 | 2:1.7.1-1 |
| debian 14 | libx11 | 2:1.7.1-1 |
| debian 9 | libx11 | 2:1.6.4-3+deb9u4 |
| echo | libx11 | 2:1.7.1-1 |
| Oracle Linux 7 | libX11 | 1.6.7-4.el7_9 |
| Oracle Linux 7 | libX11-common | 1.6.7-4.el7_9 |
| Oracle Linux 7 | libX11-devel | 1.6.7-4.el7_9 |
| Oracle Linux 8 | libX11 | 1.6.8-5.el8 |
| Oracle Linux 8 | libX11-common | 1.6.8-5.el8 |
| Oracle Linux 8 | libX11-devel | 1.6.8-5.el8 |
| Oracle Linux 8 | libX11-xcb | 1.6.8-5.el8 |
| Red Hat | libX11 | no fix listed |
| Red Hat | libX11-common | no fix listed |
| Red Hat | libX11-devel | no fix listed |
| rocky 8 | libX11 | 1.6.8-5.el8 |
| rocky 8 | libX11-common | 1.6.8-5.el8 |
| rocky 8 | libX11-devel | 1.6.8-5.el8 |
| rocky 8 | libX11-xcb | 1.6.8-5.el8 |
| ubuntu 14.04-ESM | libx11 | 2:1.6.2-1ubuntu2.1+esm2 |
| ubuntu 16.04-ESM | libx11 | 2:1.6.3-1ubuntu2.2+esm1 |
| ubuntu 18.04 | libx11 | 2:1.6.4-3ubuntu0.4 |
| ubuntu 18.04-ESM | libx11 | 2:1.6.4-3ubuntu0.4 |
| ubuntu 20.04 | libx11 | 2:1.6.9-2ubuntu1.2 |
| ubuntu 20.04-ESM | libx11 | 2:1.6.9-2ubuntu1.2 |
| ubuntu 20.10 | libx11 | 2:1.6.12-1ubuntu0.1 |
| ubuntu 21.04 | libx11 | 2:1.7.0-2ubuntu0.1 |
| ubuntu 21.10 | libx11 | 1.7.0-2ubuntu1 |
| ubuntu 22.04 | libx11 | 1.7.0-2ubuntu1 |
References
- http://packetstormsecurity.com/files/162737/libX11-Insufficient-Length-Check-Injection.html
- http://seclists.org/fulldisclosure/2021/May/52
- http://www.openwall.com/lists/oss-security/2021/05/18/2
- https://access.redhat.com/security/cve/CVE-2021-31535
- https://bugzilla.redhat.com/show_bug.cgi?id=1961822
- https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-31535
- https://errata.almalinux.org/8/ALSA-2021-4326.html
- https://errata.rockylinux.org/RLSA-2021:4326
All 30 references
- https://gitlab.freedesktop.org/xorg/lib/libx11/-/commit/8d2e02ae650f00c4a53deb625211a0527126c605
- https://linux.oracle.com/cve/CVE-2021-31535.html
- https://linux.oracle.com/errata/ELSA-2021-4326.html
- https://lists.apache.org/thread.html/r61db8e7dcb56dc000a5387a88f7a473bacec5ee01b9ff3f55308aacc@%3Cdev.kafka.apache.org%3E
- https://lists.apache.org/thread.html/r61db8e7dcb56dc000a5387a88f7a473bacec5ee01b9ff3f55308aacc@%3Cusers.kafka.apache.org%3E
- https://lists.apache.org/thread.html/rbf4ce74b0d1fa9810dec50ba3ace0caeea677af7c27a97111c06ccb7@%3Cdev.kafka.apache.org%3E
- https://lists.apache.org/thread.html/rbf4ce74b0d1fa9810dec50ba3ace0caeea677af7c27a97111c06ccb7@%3Cusers.kafka.apache.org%3E
- https://lists.debian.org/debian-lts-announce/2021/05/msg00021.html
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/TEOT4RLB76RVPJQKGGTIKTBIOLHX2NR6/
- https://lists.freedesktop.org/archives/xorg/
- https://lists.x.org/archives/xorg-announce/2021-May/003088.html
- https://nvd.nist.gov/vuln/detail/CVE-2021-31535
- https://security.gentoo.org/glsa/202105-16
- https://security.netapp.com/advisory/ntap-20210813-0001/
- https://ubuntu.com/security/notices/USN-4966-1
- https://ubuntu.com/security/notices/USN-4966-2
- https://unparalleled.eu/blog/2021/20210518-using-xterm-to-navigate-the-huge-color-space/
- https://unparalleled.eu/publications/2021/advisory-unpar-2021-1.txt
- https://www.cve.org/CVERecord?id=CVE-2021-31535
- https://www.debian.org/security/2021/dsa-4920
- https://www.openwall.com/lists/oss-security/2021/05/18/2
- https://www.openwall.com/lists/oss-security/2021/05/18/3