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CVE-2026-50257

Xorg-x11-server: xorg-x11-server-xwayland: xorg-x11-server: use-after-free in misyncdestroyfence()

Published: Jun 5, 2026Updated: Jun 8, 2026 Sources: CVE List NVD
NVD MITRE
7.8CVSS
HIGH

A use-after-free flaw was found in the X.Org X server and Xwayland in miSyncDestroyFence(). A client that sets up multiple fence triggers can trigger a use-after-free function pointer call. An attacker would connect to the X server to set up a fence and await that fence, then a second X connection destroys the fence, causing the use-after-free. This may be used to crash the server, or for privilege escalation if the X server runs as root.

EPSS Score
0.0%
Top 97.5%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Patch Available

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

Weaknesses

CWE-416

Affected Products

Red Hat Enterprise Linux 10
Red Hat
Operating Systems / linux-distro
Red Hat Enterprise Linux 6
Red Hat
Operating Systems / linux-distro
Red Hat Enterprise Linux 7
Red Hat
Operating Systems / linux-distro
Red Hat Enterprise Linux 8
Red Hat
Operating Systems / linux-distro
Red Hat Enterprise Linux 9
Red Hat
Operating Systems / linux-distro
red hatcommercialUSOperating Systemsaka red hat
and 3 more affected products View all →

Attack Graph

Products CVE Techniques Tactics

Click technique nodes to view MITRE ATT&CK details. Scroll to zoom, drag to pan.

Exploitability

Official Patch Available

MITRE ATT&CK

2 techniques
Initial Access
Privilege Escalation
View detailed technique mapping

References

https://access.redhat.com/security/cve/CVE-2026-50257
access.redhat.com
https://bugzilla.redhat.com/show_bug.cgi?id=2485382
bugzilla.redhat.com
https://gitlab.freedesktop.org/xorg/xserver/-/commit/f5abfb61994471023d8c6470428c8e30c411cc0b
gitlab.freedesktop.org
and 2 more references View all →

Timeline

Published
Jun 5, 2026
Last Updated
Jun 8, 2026
News mentions
1

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