Xorg-x11-server: xorg-x11-server-xwayland: xorg-x11-server: use-after-free in misyncdestroyfence()_CVE-2026-50257

7.8 / 10

HIGH

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

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.

Basic Information

ID CVE-2026-50257

Source redhat

Published Jun 5, 2026 at 10:31

Affected Product

Vendor Red Hat

Product Red Hat Enterprise Linux 10

CWE Classification

CWE-416

References

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    "published": "2026-06-05T10:31:22.052Z",
    "modified": "2026-06-05T10:31:22.052Z",
    "type": "cve",
    "title": "Xorg-x11-server: xorg-x11-server-xwayland: xorg-x11-server: use-after-free in misyncdestroyfence()",
    "source": "redhat",
    "references": "https://access.redhat.com/security/cve/CVE-2026-50257\nhttps://bugzilla.redhat.com/show_bug.cgi?id=2485382\nhttps://gitlab.freedesktop.org/xorg/xserver/-/commit/f5abfb61994471023d8c6470428c8e30c411cc0b\nhttps://lists.x.org/archives/xorg-announce/2026-June/003702.html\nhttps://redhat.atlassian.net/browse/PSIRTSUPT-16950",
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