CVE-2026-50261

HIGH
MEDIUM Priority: 0.01 BB Relevance: 41/100
Published: 2026-06-05 Modified: 2026-11-04 First seen: 2026-11-04 Status: active

Attack Surface

Low Complexity No Interaction Conf. Impact Integ. Impact

CVSS Vector Breakdown

AV: Local
AC: Low
PR: Low
UI: None
S: Unchanged
C: High
I: High
A: High

Description

A use-after-free flaw was found in the X.Org X server and Xwayland in SyncChangeCounter(). A client that sets up multiple SyncCounters can trigger a use-after-free when destroying those counters via a second client connection while changing those counters. This may be used to crash the server, or for privilege escalation if the X server runs as root.

Weakness Classification (1)

Affected Software (6)

References & Advisories (34)

https://access.redhat.com/errata/RHSA-2026:26562
vendor-advisory x_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:26566
vendor-advisory x_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:26590
vendor-advisory x_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:26610
vendor-advisory x_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:26709
vendor-advisory x_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:28923
vendor-advisory x_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:29844
vendor-advisory x_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:36083
vendor-advisory x_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:36085
vendor-advisory x_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:36086
vendor-advisory x_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:36087
vendor-advisory x_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:36632
vendor-advisory x_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:36633
vendor-advisory x_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:36634
vendor-advisory x_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:36768
vendor-advisory x_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:36791
vendor-advisory x_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:36792
vendor-advisory x_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:36798
vendor-advisory x_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:38502
vendor-advisory x_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:38810
vendor-advisory x_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:46377
vendor-advisory x_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:46382
vendor-advisory x_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:46385
vendor-advisory x_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:46392
vendor-advisory x_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:46456
vendor-advisory x_refsource_REDHAT
Showing 25 of 34 references

Bug Bounty Relevance

41 / 100
✓ Low complexity
✓ No user interaction

CVSS Score

7.8 / 10.0 v3.1
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS — Exploitation Probability

0.15%
Raw Score 0.001540
Percentile 4.6%
Date 2026-11-13

EPSS Trend

2026-11-13
0.00154
2026-11-12
0.00154
2026-11-10
0.00154
2026-11-09
0.00154
2026-11-08
0.00154
2026-11-07
0.00154
2026-11-06
0.00154
2026-11-05
0.00154
2026-11-04
0.00154

Intelligence Sources

mitre ref →
nvd ref →