CVE-2021-31535
libx11 - security update
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.
How to fix CVE-2021-31535
To remediate CVE-2021-31535, upgrade the affected package to a fixed version below.
- —upgrade to 1.6.12-r1 or later
- —upgrade to 2:1.7.1-1 or later
- —upgrade to 2:1.6.4-3+deb9u4 or later
- —upgrade to 2:1.6.7-1+deb10u2 or later
Is CVE-2021-31535 being exploited?
Moderate — EPSS is 5.5%. Track this CVE but it's not at the top of the prioritisation list.
Affected packages (4)
- from 0, < 1.6.12-r1
- from 0, < 2:1.7.1-1
- from 0, < 2:1.6.4-3+deb9u4
- from 0, < 2:1.6.7-1+deb10u2
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 3.1 | CRITICAL9.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |