CVE-2026-50257

HIGH EPSS 3.5%
Published Jun 5, 20263w ago · Modified Jun 24, 20261w ago
7.8 CVSS 3.1
High
Find Similar
Published Jun 5, 2026 3w ago
Last Modified Jun 24, 2026 1w ago

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 Details

Base Score
7.8
Exploitability
1.8
Impact
5.9
Vector string
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Attack Vector Local
Attack Complexity Low
Privileges Required Low
User Interaction None
Scope Unchanged
Confidentiality High
Integrity High
Availability High

Threat Intelligence

EPSS Exploit Probability
3.5% percentile
Exploit & Patch Status
No Known Exploit
Patch Available

Weaknesses 1

CWE-416 Use After Free Memory Safety

Affected Products 6

VendorProductVersionRange
x.orgx_server* <21.1.23
x.orgxwayland* <24.1.12
redhatenterprise_linux7.0any
redhatenterprise_linux8.0any
redhatenterprise_linux9.0any
redhatenterprise_linux10.0any

References 11

Remediation

  • gitlab.freedesktop.org https://gitlab.freedesktop.org/xorg/xserver/-/commit/f5abfb61994471023d8c6470428c8e30c411cc0b
    Patch