Xorg: xwayland: heap overflow in xkbwritekeysyms()

Description

A heap overflow flaw was found in X.Org and Xwayland. The computation of the length in XkbSizeKeySyms() differs from what is written in XkbWriteKeySyms(), which may lead to a heap-based buffer overflow.

Timeline

Scores

EPSS (exploitation in 30 days)

0.44% · top 61% of all CVEs (12 Nov 2026)

CISA SSVC

Exploitation: none · Automatable: no · Technical impact: total

The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.8.

Affected products

• xserver

  • affected < 21.1.16
  • affected 22.0.0 – < 24.1.6

• Red Hat · Red Hat Enterprise Linux 10

  • unaffected 0:24.1.5-3.el10_0 – < *

• Red Hat · Red Hat Enterprise Linux 6 Extended Lifecycle Support - EXTENSION

  • unaffected 0:1.1.0-25.el6_10 – < *

• Red Hat · Red Hat Enterprise Linux 7 Extended Lifecycle Support

  • unaffected 0:1.8.0-36.el7_9 – < *

• Red Hat · Red Hat Enterprise Linux 7 Extended Lifecycle Support

  • unaffected 0:1.20.4-30.el7_9 – < *

• Red Hat · Red Hat Enterprise Linux 8

  • unaffected 0:1.13.1-15.el8_10 – < *

• Red Hat · Red Hat Enterprise Linux 8.2 Advanced Update Support

  • unaffected 0:1.9.0-15.el8_2.13 – < *

• Red Hat · Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support

  • unaffected 0:1.11.0-8.el8_4.12 – < *

• Red Hat · Red Hat Enterprise Linux 8.4 Telecommunications Update Service

  • unaffected 0:1.11.0-8.el8_4.12 – < *

• Red Hat · Red Hat Enterprise Linux 8.4 Update Services for SAP Solutions

  • unaffected 0:1.11.0-8.el8_4.12 – < *

• Red Hat · Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support

  • unaffected 0:1.12.0-6.el8_6.13 – < *

• Red Hat · Red Hat Enterprise Linux 8.6 Telecommunications Update Service

  • unaffected 0:1.12.0-6.el8_6.13 – < *

• Red Hat · Red Hat Enterprise Linux 8.6 Update Services for SAP Solutions

  • unaffected 0:1.12.0-6.el8_6.13 – < *

• Red Hat · Red Hat Enterprise Linux 8.8 Extended Update Support

  • unaffected 0:1.12.0-15.el8_8.12 – < *

• Red Hat · Red Hat Enterprise Linux 9

  • unaffected 0:1.14.1-1.el9_5.1 – < *

• Red Hat · Red Hat Enterprise Linux 9

  • unaffected 0:1.20.11-28.el9_6 – < *

• Red Hat · Red Hat Enterprise Linux 9

  • unaffected 0:23.2.7-3.el9_6 – < *

• Red Hat · Red Hat Enterprise Linux 9.0 Update Services for SAP Solutions

  • unaffected 0:1.11.0-22.el9_0.13 – < *

• Red Hat · Red Hat Enterprise Linux 9.2 Extended Update Support

  • unaffected 0:1.12.0-14.el9_2.10 – < *

• Red Hat · Red Hat Enterprise Linux 9.4 Extended Update Support

  • unaffected 0:1.13.1-8.el9_4.5 – < *

• Red Hat · Red Hat Enterprise Linux 6

  All versions: unknown

• Red Hat · Red Hat Enterprise Linux 8

  All versions: unaffected

• Red Hat · Red Hat Enterprise Linux 8

  All versions: unaffected

What to do

Workaround: Mitigation for this issue is either not available or the currently available options don't meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.

Sources

The same CVE in the primary databases and aggregators, to check against.

• CVE.org record (opens in a new tab)
• CVE List JSON (GitHub) (opens in a new tab)
• NVD (opens in a new tab)
• FIRST EPSS (opens in a new tab)
• EUVD EUVD-2025-5403 (opens in a new tab)
• OSV.dev (opens in a new tab)
• GitHub Advisories (opens in a new tab)
• CIRCL Vulnerability-Lookup (opens in a new tab)

Badge for a README or a ticket

[![CVE-2025-26596](https://cveledger.app/badge/CVE-2025-26596.svg)](https://cveledger.app/cve/CVE-2025-26596)

Record last updated 4 Nov 2026, 21:32 UTC.