RHSA-2026:99754: Important: libX11 security update
The libX11 packages contain the core X11 protocol client library.Security Fix(es): libX11: libX11: Heap-based buffer overflow via malicious X server (CVE-2026-88806) For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.
Affected Software
Event History
Frequently Asked Questions
What does an attacker need to exploit this issue?
An attacker would need to control or operate a malicious X server that a vulnerable libX11 client connects to. The flaw is a heap-based buffer overflow triggered through the X11 protocol client library.
Which systems are exposed?
Systems are exposed when applications using the affected libX11 packages connect to an untrusted or malicious X server. The provided advisory does not identify affected package versions, configurations, or products.
How can I determine whether my environment is affected?
Identify hosts with libX11 packages installed and determine whether their X11 client applications may connect to X servers that are not trusted. Consult the RHSA-2026:99754 erratum for the applicable package updates and affected product details.