RLSA-2026:91366: Important: libX11 security update

Q: Which systems are realistically exposed to this issue?

Systems using the libX11 core X11 protocol client library are exposed when they connect to an attacker-controlled or malicious X server. The vulnerable component is the libX11 package in Rocky Linux.

Q: What does an attacker need to exploit the vulnerability?

An attacker needs to cause a vulnerable libX11 client to interact with a malicious X server. The CVSS vector indicates network reachability, no required privileges, high attack complexity, and required user interaction.

Q: How can I determine whether I am affected?

Check whether the system has libX11 packages installed and whether X11 client applications connect to X servers that may be untrusted or attacker-controlled. The advisory identifies the affected issue as CVE-2026-88806.

Published Oct 30, 2026

Updated

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

1 affected componentFixes available

rocky-linux/libx11<0:1.8.10-1.el10_2.1

0:1.8.10-1.el10_2.1

Remediation

Recommended actions to resolve this vulnerability, in priority order.

Upgrade
Upgrade rocky-linux/libX11 to a version that resolves this vulnerability.
Fixed in 0:1.8.10-1.el10_2.1

Event History

Oct 30, 2026

Advisory Published

via OSV·12:08 PM

Data Sourced

via OSV·12:08 PM

DescriptionSeverityAffected Software

Child vulnerabilities

Contains the following vulnerabilities.

CVE-2026-88806

Frequently Asked Questions

Which systems are realistically exposed to this issue?

Systems using the libX11 core X11 protocol client library are exposed when they connect to an attacker-controlled or malicious X server. The vulnerable component is the libX11 package in Rocky Linux.

What does an attacker need to exploit the vulnerability?

An attacker needs to cause a vulnerable libX11 client to interact with a malicious X server. The CVSS vector indicates network reachability, no required privileges, high attack complexity, and required user interaction.

How can I determine whether I am affected?

Check whether the system has libX11 packages installed and whether X11 client applications connect to X servers that may be untrusted or attacker-controlled. The advisory identifies the affected issue as CVE-2026-88806.

RLSA-2026:91366: Important: libX11 security update

Affected Software

Remediation

Event History

Child vulnerabilities

Frequently Asked Questions

Which systems are realistically exposed to this issue?

What does an attacker need to exploit the vulnerability?

How can I determine whether I am affected?

Company

Resources

Contact

Frequently Asked Questions

Which systems are realistically exposed to this issue?

What does an attacker need to exploit the vulnerability?

How can I determine whether I am affected?