Junglewise Threat Intelligence

CVE-2026-34003: X.Org X server out-of-bounds memory access in XKB request validation

CVE-2026-34003 · Severity: high · CVSS 7.8 · Published 2026-04-23

Technologies: X.Org Foundation X Server, X.Org Foundation Xwayland, Tigervnc. Vendors: X.Org Foundation, X.Org, Tigervnc.

Executive brief

A security vulnerability has been identified in the X.Org X server, a fundamental component used to manage graphical displays and user input on Linux systems. A local user could exploit this flaw to crash the system or potentially access sensitive information stored in memory. This could lead to a disruption of services or unauthorized data exposure on affected workstations and servers.

Technical details

An out-of-bounds (OOB) read vulnerability (CWE-125) exists in the X.Org X server's XKB (X Keyboard Extension) key types request validation logic. The flaw is triggered when the server processes a specially crafted XKB request from a local client. Because the server fails to properly validate the request parameters, it may access memory outside of the intended buffer. This can result in a server crash (Denial of Service) or the exposure of sensitive memory contents to the local attacker. The vulnerability affects standard X.Org servers, Xwayland, and TigerVNC components that incorporate X server code. Patches have been released by major distributions including Red Hat.

Affected products

  • X.Org X server All versions prior to April 2026 patches
  • X.Org Xwayland
  • TigerVNC TigerVNC

Timeline

  • 2026-04-23: disclosed: CVE published and reported by Red Hat
  • 2026-04-27: patched: Red Hat released security updates for RHEL 9 (RHSA-2026:10739)
  • 2026-04-28: patched: Red Hat released security updates for RHEL 10 (RHSA-2026:11352)

References

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