Vulnerability · Published May 27, 2021 · Assigned by mitre
CVE-2021-31535
Critical 9.8
In plain English
A critical-severity security flaw in the libX11 package (AlmaLinux). There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 10.4% (higher than 96% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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 & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux:8 | libX11 | 1.6.8-5.el8 | ALSA-2021:4326 |
| AlmaLinux:8 | libX11-common | 1.6.8-5.el8 | ALSA-2021:4326 |
| AlmaLinux:8 | libX11-devel | 1.6.8-5.el8 | ALSA-2021:4326 |
| AlmaLinux:8 | libX11-xcb | 1.6.8-5.el8 | ALSA-2021:4326 |
| Alpine:v3.20 | libx11 | 1.7.1-r0 | ALPINE-CVE-2021-31535 |
| Alpine:v3.21 | libx11 | 1.7.1-r0 | ALPINE-CVE-2021-31535 |
| Alpine:v3.22 | libx11 | 1.7.1-r0 | ALPINE-CVE-2021-31535 |
| Alpine:v3.23 | libx11 | 1.7.1-r0 | ALPINE-CVE-2021-31535 |
| Alpine:v3.24 | libx11 | 1.7.1-r0 | ALPINE-CVE-2021-31535 |
| Debian:12 | libx11 | 2:1.7.1-1 | DEBIAN-CVE-2021-31535 |
| Debian:13 | libx11 | 2:1.7.1-1 | DEBIAN-CVE-2021-31535 |
| Debian:14 | libx11 | 2:1.7.1-1 | DEBIAN-CVE-2021-31535 |
| Rocky Linux:8 | libX11 | 0:1.6.8-5.el8 | RLSA-2021:4326 |
Affected products (as reported)
References
- https://unparalleled.eu/publications/2021/advisory-unpar-2021-1.txt x_refsource_MISC
- https://lists.freedesktop.org/archives/xorg/ x_refsource_MISC
- [oss-security] 20210518 libX11 security advisory: May 18, 2021 mailing-list, x_refsource_MLIST
- 20210520 CVE-2021-31535 libX11 Insufficient Length Checks PoC and Archeology mailing-list, x_refsource_FULLDISC
- http://packetstormsecurity.com/files/162737/libX11-Insufficient-Length-Check-Injection.html x_refsource_MISC
- [debian-lts-announce] 20210524 [SECURITY] [DLA 2666-1] libx11 security update mailing-list, x_refsource_MLIST
- DSA-4920 vendor-advisory, x_refsource_DEBIAN
- GLSA-202105-16 vendor-advisory, x_refsource_GENTOO
- https://www.openwall.com/lists/oss-security/2021/05/18/3 x_refsource_MISC
- https://www.openwall.com/lists/oss-security/2021/05/18/2 x_refsource_MISC
- https://unparalleled.eu/blog/2021/20210518-using-xterm-to-navigate-the-huge-color-space/ x_refsource_MISC
- https://lists.x.org/archives/xorg-announce/2021-May/003088.html x_refsource_MISC
- https://gitlab.freedesktop.org/xorg/lib/libx11/-/commit/8d2e02ae650f00c4a53deb625211a0527126c605 x_refsource_MISC
- https://security.netapp.com/advisory/ntap-20210813-0001/ x_refsource_CONFIRM
- FEDORA-2021-62bb9998b2 vendor-advisory, x_refsource_FEDORA
- [kafka-dev] 20210831 Security vulnerabilities in kafka:2.13-2.6.0/2.7.0 docker image mailing-list, x_refsource_MLIST
- [kafka-users] 20210831 Security vulnerabilities in kafka:2.13-2.6.0/2.7.0 docker image mailing-list, x_refsource_MLIST
- [kafka-users] 20210901 Re: [EXTERNAL] Re: Security vulnerabilities in kafka:2.13-2.6.0/2.7.0 docker image mailing-list, x_refsource_MLIST
- [kafka-dev] 20210901 Re: [EXTERNAL] Re: Security vulnerabilities in kafka:2.13-2.6.0/2.7.0 docker image mailing-list, x_refsource_MLIST