CVE-2026-50257
Xorg-x11-server: xorg-x11-server-xwayland: xorg-x11-server: use-after-free in misyncdestroyfence()
CVSS Score
7.8
EPSS Score
0.0%
EPSS Percentile
2th
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.
| CWE | CWE-416 |
| Vendor | red hat |
| Product | red hat enterprise linux 10 |
| Published | Jun 5, 2026 |
| Last Updated | Jun 9, 2026 |
Stay Ahead of the Next One
Get instant alerts for red hat red hat enterprise linux 10
Be the first to know when new high vulnerabilities affecting red hat red hat enterprise linux 10 are published — delivered to Slack, Telegram or Discord.
Get Free Alerts →
Free · No credit card · 60 sec setup
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-2026-50257 bugzilla.redhat.com: https://bugzilla.redhat.com/show_bug.cgi?id=2485382 gitlab.freedesktop.org: https://gitlab.freedesktop.org/xorg/xserver/-/commit/f5abfb61994471023d8c6470428c8e30c411cc0b 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.