CVE-2026-88806: libX11 XkbGetMap Reply Heap-based Buffer Overflow
A malicious X server could exploit a buffer overflow in libX11 before 1.8.14 during handling of XkbGetMap overflowing the keysymmap.
Other sources
libX11 XkbGetMap Reply Heap-based Buffer Overflow
— Microsoft
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 1.8.7-2 - Upgrade
Upgrade
libX11to a version that resolves this vulnerability.Fixed in 1.8.14
Event History
Frequently Asked Questions
Which systems are exposed?
Systems using libX11 versions earlier than 1.8.14 may be exposed when they connect to a malicious X server. The issue affects processing of an XkbGetMap reply from that server.
What does exploitation require?
An attacker must control or operate a malicious X server that the affected client connects to. The CVSS vector also indicates user interaction is required.
How can I determine whether an installation is affected?
Check the installed libX11 version. Versions before 1.8.14 are affected according to the available information.