CVE-2026-50258
Xorg-x11-server: xorg-x11-server-xwayland: xorg-x11-server: stack buffer overflow in xkb key types due to unchecked shift levels
CVSS Score
7.8
EPSS Score
0.0%
EPSS Percentile
0th
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.
| CWE | CWE-121 |
| Vendor | red hat |
| Product | red hat enterprise linux 10 |
| Published | Jun 5, 2026 |
| Last Updated | Jun 8, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High
Affected Versions
Red Hat / Red Hat Enterprise Linux 10
All versions affected Red Hat / Red Hat Enterprise Linux 6
All versions affected Red Hat / Red Hat Enterprise Linux 7
All versions affected Red Hat / Red Hat Enterprise Linux 8
All versions affected Red Hat / Red Hat Enterprise Linux 8
All versions affected Red Hat / Red Hat Enterprise Linux 9
All versions affected Red Hat / Red Hat Enterprise Linux 9
All versions affected References
access.redhat.com: https://access.redhat.com/security/cve/CVE-2026-50258 bugzilla.redhat.com: https://bugzilla.redhat.com/show_bug.cgi?id=2485383 gitlab.freedesktop.org: https://gitlab.freedesktop.org/xorg/xserver/-/commit/543e108516428fc8c3bea91d6563ad266f9a801e lists.x.org: https://lists.x.org/archives/xorg-announce/2026-June/003702.html redhat.atlassian.net: https://redhat.atlassian.net/browse/PSIRTSUPT-16950
Credits
Upstream acknowledges Anonymous (Trend Micro Zero Day Initiative) as the original reporter.