CVE-2026-50258

A stack-based buffer overflow flaw was found in the X.Org X server and Xwayland. The X server has multiple stack buffers sized XkbMaxShiftLevel * XkbNumKbdGroups but CheckKeyTypes() does not verify or clamp non-canonical key types to XkbMaxShiftLevel. A client can change key types to excessive shift levels and trigger stack overflows. This is caused by an incomplete fix of CVE-2025-26597. This may be used to crash the server, or for privilege escalation if the X server runs as root.
References
Link Resource
https://access.redhat.com/errata/RHSA-2026:26562
https://access.redhat.com/errata/RHSA-2026:26566
https://access.redhat.com/errata/RHSA-2026:26590
https://access.redhat.com/errata/RHSA-2026:26610
https://access.redhat.com/errata/RHSA-2026:26709
https://access.redhat.com/errata/RHSA-2026:28923
https://access.redhat.com/errata/RHSA-2026:29844
https://access.redhat.com/errata/RHSA-2026:36083
https://access.redhat.com/errata/RHSA-2026:36085
https://access.redhat.com/errata/RHSA-2026:36086
https://access.redhat.com/errata/RHSA-2026:36087
https://access.redhat.com/errata/RHSA-2026:36632
https://access.redhat.com/errata/RHSA-2026:36633
https://access.redhat.com/errata/RHSA-2026:36634
https://access.redhat.com/errata/RHSA-2026:36768
https://access.redhat.com/errata/RHSA-2026:36791
https://access.redhat.com/errata/RHSA-2026:36792
https://access.redhat.com/errata/RHSA-2026:36798
https://access.redhat.com/errata/RHSA-2026:38502
https://access.redhat.com/errata/RHSA-2026:38810
https://access.redhat.com/errata/RHSA-2026:46377
https://access.redhat.com/errata/RHSA-2026:46382
https://access.redhat.com/errata/RHSA-2026:46385
https://access.redhat.com/errata/RHSA-2026:46392
https://access.redhat.com/errata/RHSA-2026:46456
https://access.redhat.com/errata/RHSA-2026:46460
https://access.redhat.com/errata/RHSA-2026:46473
https://access.redhat.com/errata/RHSA-2026:49519
https://access.redhat.com/security/cve/CVE-2026-50258 Third Party Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=2485383 Issue Tracking Third Party Advisory
https://gitlab.freedesktop.org/xorg/xserver/-/commit/543e108516428fc8c3bea91d6563ad266f9a801e Patch
https://lists.x.org/archives/xorg-announce/2026-June/003702.html Mailing List Third Party Advisory
https://redhat.atlassian.net/browse/PSIRTSUPT-16950 Permissions Required
https://access.redhat.com/errata/RHSA-2026:26562
https://access.redhat.com/errata/RHSA-2026:26566
https://access.redhat.com/errata/RHSA-2026:26590
https://access.redhat.com/errata/RHSA-2026:26610
https://access.redhat.com/errata/RHSA-2026:26709
https://access.redhat.com/errata/RHSA-2026:28923
https://access.redhat.com/errata/RHSA-2026:29844
https://access.redhat.com/errata/RHSA-2026:36083
https://access.redhat.com/errata/RHSA-2026:36085
https://access.redhat.com/errata/RHSA-2026:36086
https://access.redhat.com/errata/RHSA-2026:36087
https://access.redhat.com/errata/RHSA-2026:36632
https://access.redhat.com/errata/RHSA-2026:36633
https://access.redhat.com/errata/RHSA-2026:36634
https://access.redhat.com/errata/RHSA-2026:36768
https://access.redhat.com/errata/RHSA-2026:36791
https://access.redhat.com/errata/RHSA-2026:36792
https://access.redhat.com/errata/RHSA-2026:36798
https://access.redhat.com/errata/RHSA-2026:38502
https://access.redhat.com/errata/RHSA-2026:38810
https://access.redhat.com/errata/RHSA-2026:46377
https://access.redhat.com/errata/RHSA-2026:46382
https://access.redhat.com/errata/RHSA-2026:46385
https://access.redhat.com/errata/RHSA-2026:46392
https://access.redhat.com/errata/RHSA-2026:46456
https://access.redhat.com/errata/RHSA-2026:46460
https://access.redhat.com/errata/RHSA-2026:46473
https://access.redhat.com/errata/RHSA-2026:49519
https://access.redhat.com/security/cve/CVE-2026-50258 Third Party Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=2485383 Issue Tracking Third Party Advisory
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-50258.json
Configurations

Configuration 1 (hide)

OR cpe:2.3:a:x.org:x_server:*:*:*:*:*:*:*:*
cpe:2.3:a:x.org:xwayland:*:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux:7.0:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux:9.0:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux:10.0:*:*:*:*:*:*:*

History

No history.

Information

Published : 2026-06-05 12:16

Updated : 2026-08-05 13:23


NVD link : CVE-2026-50258

Mitre link : CVE-2026-50258

CVE.ORG link : CVE-2026-50258


JSON object : View

Products Affected

x.org

  • x_server
  • xwayland

redhat

  • enterprise_linux
CWE
CWE-121

Stack-based Buffer Overflow