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Enterprise LinuxOperating system · Redhat

CVE-2026-34002

CRITICAL · 9.1 CVSS v3.1 Published 2026-05-05
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
A flaw was found in the X.Org X server. This vulnerability, an out-of-bounds read, affects the XKB (X Keyboard Extension) modifier map handling. An attacker with access to the X11 server can exploit this by sending a malformed request, which causes the server to read beyond its intended memory boundaries. This can lead to the exposure of sensitive information or cause the server to crash, resulting in a denial of service.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Out-of-bounds read vulnerability in the XKB (X Keyboard Extension) modifier map handling of the X.Org X server. An attacker with X11 access can send a malformed request causing the server to read beyond intended memory boundaries, leading to sensitive information disclosure or denial of service via server crash.

MitigationApply vendor patches for X.Org X server addressing the XKB modifier map bounds checking issue. As a temporary mitigation, restrict X11 access to trusted users and consider disabling the XKB extension if not required.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Enterprise LinuxOperating system
Affected:= 6.0= 7.0= 8.0= 9.0= 10.0
X ServerApplication
Affected:all versions

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Verify X.org X Server is installed
    Check for X server packages using your package manager (e.g., 'rpm -qa | grep -i xorg-x11-server' on RHEL systems, or check for Xorg/X11 processes running with 'ps aux | grep Xorg')
    Affected if X server is installed and running
  2. Confirm XKB extension is enabled
    Check if XKB is active by examining X server configuration or running 'xdpyinfo | grep -i xkb' from a client to query server extensions
    Affected if XKB extension is loaded by the X server (required for the vulnerability to be exploitable)
  3. Determine X server version
    Run 'Xorg -version' or check the installed package version (e.g., 'rpm -q xorg-x11-server-Xorg')
    Affected if The installed version matches any version (all versions of X.org X Server are affected per the advisory)
  4. Assess X11 access exposure
    Check who can connect to the X server using 'xauth list' or review .Xauthority files, and check for unauthenticated access with 'xhost +' which would allow any user X11 access
    Affected if Untrusted users or network clients have X11 access to the server

The environment is affected if an X.org X Server with XKB extension enabled is running and accessible to untrusted users who could send malformed requests.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply vendor patches for X.Org X server addressing the XKB modifier map bounds checking issue. As a temporary mitigation, restrict X11 access to trusted users and consider disabling the XKB extension if not required.

Fix this in Enterprise Linux Scoped from the published advisory
  • Consultation8.0 h
  • Implementation16.0 h
  • Testing8.0 h
  • Review / QA4.0 h
36.0 hours of engineering $6,400
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-34002 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data