CVE-2026-50258
HIGHXorg-x11-server: xorg-x11-server-xwayland: xorg-x11-server: stack buffer overflow in xkb key types due to unchecked shift levels
Title source: cnaDescription
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 (5)
Core 5
Core References
Vdb Entry, X_Refsource_Redhat vdb-entry
x_refsource_redhat
https://access.redhat.com/security/cve/CVE-2026-50258
Issue Tracking, X_Refsource_Redhat issue-tracking
x_refsource_redhat
RHBZ#2485383
https://bugzilla.redhat.com/show_bug.cgi?id=2485383
Scores
CVSS v3
7.8
EPSS
0.0021
EPSS Percentile
10.7%
Attack Vector
LOCAL
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CISA SSVC
Vulnrichment
Exploitation
none
Automatable
no
Technical Impact
total
Details
CWE
CWE-121
Status
published
Products (11)
Red Hat/Red Hat Enterprise Linux 10
Red Hat/Red Hat Enterprise Linux 6
Red Hat/Red Hat Enterprise Linux 7
Red Hat/Red Hat Enterprise Linux 8
Red Hat/Red Hat Enterprise Linux 9
redhat/enterprise_linux
7.0
redhat/enterprise_linux
8.0
redhat/enterprise_linux
9.0
redhat/enterprise_linux
10.0
x.org/x_server
< 21.1.23
... and 1 more
Published
Jun 05, 2026
Tracked Since
Jun 05, 2026