CVE-2026-50257
Last modified
CVE-2026-50257 is a high-severity vulnerability rated 7.8/10 on the CVSS scale. 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. EPSS estimates a 0.14% chance of exploitation in the next 30 days.
Description
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.
Metrics
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Weakness Enumeration
Affected Software
| Vendor | Product | Versions |
|---|---|---|
| X.Org | X Server | < 21.1.23 |
| X.Org | Xwayland | < 24.1.12 |
| Redhat | Enterprise Linux | 7.0 |
| Redhat | Enterprise Linux | 8.0 |
| Redhat | Enterprise Linux | 9.0 |
| Redhat | Enterprise Linux | 10.0 |
References
- https://access.redhat.com/security/cve/CVE-2026-50257Third Party Advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=2485382Issue Tracking, Third Party Advisory
- https://lists.x.org/archives/xorg-announce/2026-June/003702.htmlMailing List, Third Party Advisory
- https://redhat.atlassian.net/browse/PSIRTSUPT-16950Permissions Required
- https://access.redhat.com/security/cve/CVE-2026-50257Third Party Advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=2485382Issue Tracking, Third Party Advisory
Timeline
- Published
- Last Modified
- Status
- Modified
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How Strix Helps
- How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
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