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CVE-2026-33999VulnerabilityPublished Updated

Red Hat Security Advisory: xorg-x11-server-Xwayland security update

Affects Red Hat xorg-serverSource GCVE Database

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Mentioned vulnerabilities

Authoritative record:CVE-2026-33999· High 7.8

Not known to be exploited · CVSS 7.8 High.

Data as of 30 Oct 2026, 11:52 UTC

CVSS 3.1 base score
7.8High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.3% chance of exploitation in 30 days – higher than 31% 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 23 Apr 2026

  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 30 Oct 2026.

What to do

Affected software

ProductAffectedFixed in
Ubuntu 26.04 LTSxorg-serverpkg:deb/ubuntu/xorg-server?arch=source&distro=resoluteOther threatsAffected
  • 2:21.1.18-1ubuntu1 – 2:21.1.22-1ubuntu1.2
4 affected builds
Fixed in–
Ubuntu 26.04 LTSxwaylandpkg:deb/ubuntu/xwayland?arch=source&distro=resoluteOther threatsAffected
  • 2:24.1.6-1ubuntu1 – 2:24.1.10-1
4 affected builds
Fixed in–
Ubuntu 25.10xorg-serverpkg:deb/ubuntu/xorg-server?arch=source&distro=questingOther threatsAffected
  • =2:21.1.16-1ubuntu1
  • =2:21.1.18-1ubuntu1
  • =2:21.1.18-1ubuntu1.1
Fixed in–
Ubuntu 25.10xwaylandpkg:deb/ubuntu/xwayland?arch=source&distro=questingOther threatsAffected
  • =2:24.1.6-1
  • =2:24.1.6-1ubuntu1
  • =2:24.1.6-1ubuntu1.1
Fixed in–
Ubuntu 24.04 LTSxorg-serverpkg:deb/ubuntu/xorg-server?arch=source&distro=nobleOther threatsAffected
  • 2:21.1.7-3ubuntu2 – 2:21.1.12-1ubuntu1.8
12 affected builds
Fixed in–
Ubuntu 24.04 LTSxwaylandpkg:deb/ubuntu/xwayland?arch=source&distro=nobleOther threatsAffected
  • 2:23.2.0-1 – 2:23.2.6-1ubuntu0.8
15 affected builds
Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Red Hat has issued an important security update for xorg-x11-server-Xwayland in Red Hat Enterprise Linux 9.2 that addresses these vulnerabilities. Users should apply the update as detailed in Red Hat advisory RHSA-2026:20547 and the referenced article https://access.redhat.com/articles/11258. No additional mitigation steps are indicated beyond applying the official patch.

Description

Xwayland is an X server for running X clients under Wayland. Security Fix(es): * xorg: xwayland: X.Org X server: Denial of Service via integer underflow in XKB compatibility map handling (CVE-2026-33999) * xwayland: xorg: X.Org X server: Information disclosure and denial of service via out-of-bounds read in XKB geometry processing. (CVE-2026-34000) * xorg: xwayland: X.Org X server: Use-after-free vulnerability leads to server crash and potential memory corruption (CVE-2026-34001) * xorg: xwayland: X.Org X server: Information disclosure or Denial of Service via out-of-bounds read in XKB modifier map handling (CVE-2026-34002) * xorg: xwayland: X.Org X server: Information exposure and denial of service via out-of-bounds memory access (CVE-2026-34003) For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

References

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