PatchSiren cyber security CVE debrief
CVE-2026-50261 Red Hat CVE debrief
CVE-2026-50261 is a HIGH severity vulnerability in X.Org X server and Xwayland. A use-after-free flaw was found in SyncChangeCounter(). A client that sets up multiple SyncCounters can trigger a use-after-free when destroying those counters via a second client connection while changing those counters. This may be used to crash the server, or for privilege escalation if the X server runs as root.
- Vendor
- Red Hat
- Product
- Red Hat Enterprise Linux 10
- CVSS
- HIGH 7.8
- CISA KEV
- Not listed in stored evidence
- Original CVE published
- 2026-06-05
- Original CVE updated
- 2026-06-05
- Advisory published
- 2026-06-05
- Advisory updated
- 2026-06-05
Who should care
Users of X.Org X server and Xwayland should apply patches or mitigations to address this vulnerability.
Technical summary
The vulnerability has a CVSS score of 7.8 and is classified as HIGH severity. The vulnerability is caused by a use-after-free flaw in SyncChangeCounter().
Defensive priority
HIGH
Recommended defensive actions
- Apply patches or updates from the vendor as soon as possible.
- Restrict access to the X server to trusted users only.
- Monitor for suspicious activity on the X server.
Evidence notes
The CVE record was published on 2026-06-05T12:16:39.617Z and modified on 2026-06-05T13:27:38.750Z.
Official resources
CVE-2026-50261 was published on 2026-06-05T12:16:39.617Z and modified on 2026-06-05T13:27:38.750Z.