---
id: CVE-2026-88806
title: >-
  A malicious X server could exploit a buffer overflow in libX11 before 1.8.14
  during handling of XkbGetMap overflowing the key_sym_map.
summary: >-
  A malicious X server could exploit a buffer overflow in libX11 before 1.8.14
  during handling of XkbGetMap overflowing the key_sym_map.
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H'
cwe:
  - CWE-122
  - CWE-787
vendor: x.org
product: libX11
affected:
  - libX11 < 1.8.14
published: '2026-09-21'
updated: '2026-09-22'
sourceUpdated: '2026-09-22T19:40:05.870'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-88806'
references:
  - url: 'https://gitlab.freedesktop.org/xorg/lib/libx11/-/merge_requests/309'
    label: meissner@suse.de
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-88806.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-88806'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2538514'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-88806'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-88806'
  - url: 'https://access.redhat.com/errata/RHSA-2026:89730'
tags:
  - nvd
  - cve.org
  - csaf
  - vex
  - red-hat
epss: 0.00202
epssPercentile: 0.10191
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-09-21T00:00:00+00:00'
ingestedAt: '2026-09-21T14:38:56.363Z'
patched:
  - enterprise_linux_appstream_v_8
---

## Overview

A malicious X server could exploit a buffer overflow in libX11 before 1.8.14 during handling of XkbGetMap overflowing the key_sym_map.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Vendor advisories

- **RHSA-2026:89730** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 8) · released 2026-10-26 · [advisory](https://access.redhat.com/errata/RHSA-2026:89730)
- **Red Hat VEX** · Important · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 9 · no fix planned: Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 9 · updated 2026-10-26 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-88806.json)