Buffer Overflow

Affecting libx11 package, versions <2:1.6.4-3+deb9u4

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NVD Description

Note: Versions mentioned in the description apply to the upstream libx11 package. See Remediation section below for Debian:9 relevant versions.

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.

Remediation

Upgrade Debian:9 libx11 to version 2:1.6.4-3+deb9u4 or higher.

References

CVSS Score

9.8
critical severity
  • Attack Vector
    Network
  • Attack Complexity
    Low
  • Privileges Required
    None
  • User Interaction
    None
  • Scope
    Unchanged
  • Confidentiality
    High
  • Integrity
    High
  • Availability
    High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CVE
CVE-2021-31535
CWE
CWE-120
Snyk ID
SNYK-DEBIAN9-LIBX11-1293571
Disclosed
27 May, 2021
Published
19 May, 2021