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VulnerabilityPublished Updated

CVE-2025-26601: xserver · Use After Free

Affects xserverSource GCVE Database

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Not known to be exploited · CVSS 7.8 High.

Data as of 5 Nov 2026, 00:01 UTC

CVSS 3.1 base score
7.8High
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CNA (redhat)CVSS 3.17.8
EPSS
0.3% chance of exploitation in 30 days – higher than 33% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 25 Feb 2025

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 5 Nov 2026.

What to do

Affected software

ProductAffectedFixed in
xserverAffected
  • =0
  • =22.0.0
Fixed in–

AI-suggested

Red Hat has released official security updates that fix this vulnerability. Users of affected Red Hat Enterprise Linux 9 versions should apply the provided patches promptly. The vendor advisory (RHSA-2025:2500) contains detailed instructions for updating affected packages. No additional mitigation steps are required beyond applying the official fix.

Description

CVE-2025-26601 is a use-after-free vulnerability in X.Org and Xwayland components of the xserver. The flaw occurs when changing an alarm's trigger values; if an error arises during the change mask evaluation, the function returns early without adding a new sync object, potentially causing a use-after-free when the alarm triggers. This vulnerability has a high severity with a CVSS score of 7.8. Red Hat has issued security updates addressing this and related vulnerabilities in xserver and xwayland.

References

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