CVE-2026-50257
7.8 HIGHA use-after-free flaw was found in the X.Org X server and Xwayland in miSyncDestroyFence()
Published: 2026-06-05 · Last updated: 2026-06-08
Severity and scoring
- CVSS
- 7.8 HIGH
- Vector
- CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- CWE
- CWE-416
Affected products
| Vendor | Product |
|---|---|
| redhat | enterprise_linux, x_server, xwayland |
| x.org | enterprise_linux, x_server, xwayland |
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.
Source: NVD
References
- [NVD]https://nvd.nist.gov/vuln/detail/CVE-2026-50257
- [Other]https://access.redhat.com/security/cve/CVE-2026-50257
- [Other]https://bugzilla.redhat.com/show_bug.cgi?id=2485382
- [Patch]https://gitlab.freedesktop.org/xorg/xserver/-/commit/f5abfb61994471023d8c6470428c8e30c411cc0b
- [Other]https://lists.x.org/archives/xorg-announce/2026-June/003702.html
- [Other]https://redhat.atlassian.net/browse/PSIRTSUPT-16950
Related CVEs
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- CVE-2026-50259 — A stack-based buffer overflow flaw was found in the X.Org X server and Xwayland (7.8 HIGH)
- CVE-2026-50258 — A stack-based buffer overflow flaw was found in the X.Org X server and Xwayland (7.8 HIGH)
- CVE-2026-50256 — A stack-based buffer overflow flaw was found in the X.Org X server and Xwayland (7.8 HIGH)
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