CVE-2026-50257

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.

Score
CVSS 3.1 7.8 High
Status
Modified - secalert@redhat.com
Published
2026-06-05
Last modified
2026-09-28
Weaknesses
CWE-416

Affected products

References

 
 
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