Use After Free Affecting xorg-x11-server-Xvfb package, versions <0:1.20.11-28.el8_10.2


Severity

Recommended
0.0
high
0
10

Based on Rocky Linux security rating.

Threat Intelligence

EPSS
0.2% (10th percentile)

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  • Snyk IDSNYK-ROCKY8-XORGX11SERVERXVFB-17389277
  • published20 Jun 2026
  • disclosed5 Jun 2026

Introduced: 5 Jun 2026

NewCVE-2026-50257  (opens in a new tab)
CWE-416  (opens in a new tab)

How to fix?

Upgrade Rocky-Linux:8 xorg-x11-server-Xvfb to version 0:1.20.11-28.el8_10.2 or higher.
This issue was patched in RLSA-2026:26709.

NVD Description

Note: Versions mentioned in the description apply only to the upstream xorg-x11-server-Xvfb package and not the xorg-x11-server-Xvfb package as distributed by Rocky-Linux. See How to fix? for Rocky-Linux:8 relevant fixed versions and status.

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 Base Scores

version 3.1