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7.8 High

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

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.

CVSS 3.1 detail

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

Exploitable with local access to the machine, with an ordinary account and without any user action; an attacker can seriously compromise confidentiality, integrity or availability.

Attack vector
Local
Attack complexity
Low
Privileges required
Low
Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

Affected products and versions

Product Affected versions Fixed in
Red Hat Enterprise Linux 10 Versions not published
Red Hat Enterprise Linux 6 Versions not published
Red Hat Enterprise Linux 7 Versions not published
Red Hat Enterprise Linux 8 Versions not published
Red Hat Enterprise Linux 9 Versions not published
Red Hat Enterprise Linux AppStream (v. 10) Versions not published
Red Hat Enterprise Linux AppStream (v. 8) Versions not published
Red Hat Enterprise Linux AppStream (v. 9) Versions not published
Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) Versions not published
Show the 28 other branches
Product Affected versions Fixed in
Red Hat Enterprise Linux CRB (v. 8) Versions not published
Red Hat Enterprise Linux CodeReady Linux Builder (v. 9) Versions not published
Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions Versions not published
Red Hat Enterprise Linux Server (v. 7 ELS) Versions not published
Red Hat Enterprise Linux Server Optional (v. 7 ELS) Versions not published
Red Hat Enterprise Linux AppStream E4S (v.9.2) Versions not published
Red Hat Enterprise Linux AppStream E4S (v.9.4) Versions not published
Red Hat Enterprise Linux AppStream EUS (v.9.6) Versions not published
Red Hat CodeReady Linux Builder EUS (v.9.6) Versions not published
Red Hat Enterprise Linux 7 Extended Lifecycle Support Versions not published
Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions Versions not published
Red Hat Enterprise Linux 9.6 Extended Update Support Versions not published
Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support Versions not published
Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On Versions not published
Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support Versions not published
Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On Versions not published
Red Hat Enterprise Linux 10.0 Extended Update Support Versions not published
Red Hat Enterprise Linux 8.8 Telecommunications Update Service Versions not published
Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions Versions not published
Red Hat Enterprise Linux AppStream EUS (v. 10.0) Versions not published
Red Hat Enterprise Linux AppStream AUS (v.8.4) Versions not published
Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.4) Versions not published
Red Hat Enterprise Linux AppStream AUS (v.8.6) Versions not published
Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.6) Versions not published
Red Hat Enterprise Linux AppStream E4S (v.8.8) Versions not published
Red Hat Enterprise Linux AppStream TUS (v.8.8) Versions not published
Red Hat Enterprise Linux CodeReady Linux Builder EUS (v. 10.0) Versions not published
Red Hat Enterprise Linux 6 Extended Lifecycle Support - EXTENSION Versions not published

References

Timeline

  1. Published
  2. Last modified

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