Buffer Overflow Vulnerability in libX11 Affects X Server Functionality
CVE-2026-88806

7.5HIGH

Key Information:

Vendor

X.org

Status
Libx11
Vendor
CVE Published:
21 September 2026

What is CVE-2026-88806?

A buffer overflow vulnerability exists in libX11 prior to version 1.8.14 that arises during the processing of XkbGetMap. An attacker controlling a malicious X server could exploit this vulnerability to overflow the key_sym_map and potentially execute arbitrary code on the host system. This flaw highlights the importance of updating to patched versions to enhance system security.

Affected Version(s)

libX11 0 < 1.8.14

References

https://gitlab.freedesktop.org/xorg/lib/libx11/-/merge_re...
patch

CVSS V3.1

Score:
7.5
Severity:
HIGH
Confidentiality:
High
Integrity:
High
Availability:
High
Attack Vector:
Network
Attack Complexity:
High
Privileges Required:
None
User Interaction:
Required
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

Adam Bedard working with TrendAI Zero Day Initiative
Claude:claude-opus-4-6
.