CVE-2026-50259Xorg-x11-server: xorg-x11-server-xwayland: xorg-x11-server: stack buffer overflow in xkb setmap request via mapwidths indexing

Description

A stack-based buffer overflow flaw was found in the X.Org X server and Xwayland. _XkbSetMapChecks() declares a fixed-size stack buffer mapWidths[256] indexed by key type index. The helper function CheckKeyTypes() writes to this buffer at a client-controlled offset, allowing a stack buffer overflow. This may be used to crash the server, or for privilege escalation if the X server runs as root.

Timeline

Scores

EPSS (exploitation in 30 days)

0.17% · top 94% of all CVEs (15 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

• Red Hat · Red Hat Enterprise Linux 10

  • unaffected 0:24.1.9-4.el10_2.2 – < *

• Red Hat · Red Hat Enterprise Linux 10.0 Extended Update Support

  • unaffected 0:24.1.5-6.el10_0.1 – < *

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

  • unaffected 0:1.1.0-25.el6_10.18 – < *

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

  • unaffected 0:1.20.4-35.el7_9 – < *

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

  • unaffected 0:1.8.0-36.el7_9.5 – < *

• Red Hat · Red Hat Enterprise Linux 8

  • unaffected 0:21.1.3-20.el8_10.2 – < *

• Red Hat · Red Hat Enterprise Linux 8

  • unaffected 0:1.20.11-28.el8_10.2 – < *

• Red Hat · Red Hat Enterprise Linux 8

  • unaffected 0:1.15.0-10.el8_10 – < *

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

  • unaffected 0:1.20.10-5.el8_4 – < *

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

  • unaffected 0:1.11.0-8.el8_4.16 – < *

• Red Hat · Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On

  • unaffected 0:1.20.10-5.el8_4 – < *

• Red Hat · Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On

  • unaffected 0:1.11.0-8.el8_4.16 – < *

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

  • unaffected 0:1.20.11-8.el8_6 – < *

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

  • unaffected 0:21.1.3-2.el8_6.7 – < *

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

  • unaffected 0:1.12.0-6.el8_6.18 – < *

• Red Hat · Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On

  • unaffected 0:1.20.11-8.el8_6 – < *

• Red Hat · Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On

  • unaffected 0:21.1.3-2.el8_6.7 – < *

• Red Hat · Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On

  • unaffected 0:1.12.0-6.el8_6.18 – < *

• Red Hat · Red Hat Enterprise Linux 8.8 Telecommunications Update Service

  • unaffected 0:1.20.11-19.el8_8 – < *

• Red Hat · Red Hat Enterprise Linux 8.8 Telecommunications Update Service

  • unaffected 0:21.1.3-13.el8_8.1 – < *

• Red Hat · Red Hat Enterprise Linux 8.8 Telecommunications Update Service

  • unaffected 0:1.12.0-15.el8_8.18 – < *

• Red Hat · Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions

  • unaffected 0:1.20.11-19.el8_8 – < *

• Red Hat · Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions

  • unaffected 0:21.1.3-13.el8_8.1 – < *

• Red Hat · Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions

  • unaffected 0:1.12.0-15.el8_8.18 – < *

• Red Hat · Red Hat Enterprise Linux 9

  • unaffected 0:24.1.9-4.el9_8.2 – < *

• Red Hat · Red Hat Enterprise Linux 9

  • unaffected 0:1.20.11-34.el9_8.2 – < *

• Red Hat · Red Hat Enterprise Linux 9

  • unaffected 0:1.15.0-7.el9_8.2 – < *

• Red Hat · Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions

  • unaffected 0:1.20.11-21.el9_2 – < *

• Red Hat · Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions

  • unaffected 0:21.1.3-10.el9_2.1 – < *

• Red Hat · Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions

  • unaffected 0:1.12.0-14.el9_2.15 – < *

• Red Hat · Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions

  • unaffected 0:1.20.11-29.el9_4 – < *

• Red Hat · Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions

  • unaffected 0:22.1.9-8.el9_4.1 – < *

• Red Hat · Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions

  • unaffected 0:1.13.1-8.el9_4.10 – < *

• Red Hat · Red Hat Enterprise Linux 9.6 Extended Update Support

  • unaffected 0:1.20.11-34.el9_6 – < *

• Red Hat · Red Hat Enterprise Linux 9.6 Extended Update Support

  • unaffected 0:23.2.7-6.el9_6.1 – < *

• Red Hat · Red Hat Enterprise Linux 9.6 Extended Update Support

  • unaffected 0:1.14.1-11.el9_6 – < *

• Red Hat · Red Hat Enterprise Linux 6

  All versions: unknown

What to do

Workaround: Mitigation for this issue is either not available or the currently available options do not 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-2026-34814 (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-2026-50259](https://cveledger.app/badge/CVE-2026-50259.svg)](https://cveledger.app/cve/CVE-2026-50259)

Record last updated 4 Nov 2026, 22:43 UTC.