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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

Published: Jun 5, 2026Updated: Jul 27, 2026 Sources: CVE List NVD BDUCWE-121
7.8HIGH
NVD MITRE
EPSS Score
0.2%
Top 94.2%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Patch Available
Self-Check
OpenVAS

Description

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.

No summary for this CVE yet.

CVSS Vector Breakdown

AV:LAC:LPR:LUI:NS:UC:HI:HA:H
Exploitability
AV:LAttack Vector
Local
AC:LAttack Complexity
Low
PR:LPrivileges Required
Low
UI:NUser Interaction
None
Scope
S:UScope
Unchanged
Impact
C:HConfidentiality
High
I:HIntegrity
High
A:HAvailability
High
Open in CVSS calculator →

Weaknesses

CWE-121

Affected Products

Red Hat Inc.
commercial·USaka redhat, Red Hat
Red Hat Enterprise Linux 10On-premOS
Operating Systems / linux-distro
Red Hat Enterprise Linux 10.0 Extended Update SupportOn-premOS
Operating Systems / linux-distro
Red Hat Enterprise Linux 7 Extended Lifecycle SupportOn-premOS
Operating Systems / linux-distro
Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update SupportOn-premOS
Operating Systems / linux-distro
Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-OnOn-premOS
Operating Systems / linux-distro
Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update SupportOn-premOS
Operating Systems / linux-distro
Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-OnOn-premOS
Operating Systems / linux-distro
Red Hat Enterprise Linux 8.8 Telecommunications Update ServiceOn-premOS
Operating Systems / linux-distro
x.org
oss-project·US
x serverOn-prem
Operating Systems / unix-bsd
xwaylandOn-prem
Operating Systems / linux-distro
Сообщество свободного программного обеспечения
oss-projectaka fsf
XWaylandOn-prem
Operating Systems / linux-distro
X.Org Foundation
oss-project·USaka libx11, xorg-server, xlib
X.Org Server
Operating Systems / unix-bsd
and 9 more affected products View all →

Exploitability

Official Patch Available
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Attack Graph

Products CVE Techniques Tactics

Click technique nodes for MITRE ATT&CK details · drag to pan · Ctrl/⌘ + scroll to zoom, or go fullscreen.

MITRE ATT&CK

1 technique
Privilege Escalation
View detailed technique mapping

References

https://access.redhat.com/security/cve/CVE-2026-50258
access.redhat.com
https://bugzilla.redhat.com/show_bug.cgi?id=2485383
bugzilla.redhat.com
https://gitlab.freedesktop.org/xorg/xserver/-/commit/543e108516428fc8c3bea91d6563ad266f9a801e
gitlab.freedesktop.org
and 34 more references View all →
News mentions
1

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