dbcve.org
FedoraOperating system · Fedoraproject

CVE-2024-0408

MEDIUM · 5.5 CVSS v3.1 Published 2024-01-18
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
57/100
Remediation priority · Elevated
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 server. The GLX PBuffer code does not call the XACE hook when creating the buffer, leaving it unlabeled. When the client issues another request to access that resource (as with a GetGeometry) or when it creates another resource that needs to access that buffer, such as a GC, the XSELINUX code will try to use an object that was never labeled and crash because the SID is NULL.

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

The X.Org server's GLX PBuffer creation fails to invoke the XACE (X Access Control Extension) hook, leaving the buffer unlabeled (no Security ID assigned). When a client subsequently requests access to this buffer (e.g., via GetGeometry) or creates dependent resources (e.g., Graphics Context), the XSELINUX subsystem attempts to use a NULL SID, causing a NULL pointer dereference crash.

MitigationApply the vendor patch to ensure the XACE hook is called during PBuffer creation, properly labeling the buffer with a valid SID before client access is permitted.

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
FedoraOperating system
Affected:= 39
Enterprise LinuxOperating system
Affected:= 6.0= 7.0= 8.0= 9.0
Enterprise Linux DesktopOperating system
Affected:= 7.0
Enterprise Linux For Ibm Z SystemsOperating system
Affected:= 7.0
Enterprise Linux For Power Big EndianOperating system
Affected:= 7.0
Enterprise Linux For Power Little EndianOperating system
Affected:= 7.0
Enterprise Linux For Scientific ComputingOperating system
Affected:= 7.0
Enterprise Linux ServerOperating system
Affected:= 7.0

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
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/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. Identify X.Org server package version
    Run 'rpm -qa | grep -i xorg-server' on RHEL-based systems or 'dpkg -l | grep -i xserver-xorg' on Debian-based systems to find the installed X.Org server package version
    Affected if The installed version matches the affected Red Hat Enterprise Linux versions (6.0, 7.0, 8.0, 9.0) or Fedora 39, and the system uses the X.Org server with GLX extension
  2. Verify GLX extension is loaded
    Run 'xdpyinfo | grep -i glx' or check X server log files (typically /var/log/Xorg.0.log) for GLX extension loading status
    Affected if GLX extension is loaded and in use, as the vulnerability specifically affects GLX PBuffer creation
  3. Check SELinux status and XSELINUX policy
    Run 'getenforce' to check if SELinux is enabled, and 'semodule -l | grep -i xselinux' to verify if the XSELINUX module is installed
    Affected if SELinux is enabled (enforcing or permissive mode) and the XSELINUX module is active, as the crash occurs in the XSELINUX subsystem when attempting to use a NULL SID
  4. Confirm PBuffer usage in GLX applications
    Review application logs or monitor for GLX PBuffer allocations using 'xrestop' or by examining /proc/<xorg_pid>/fd if GLX applications are running
    Affected if Applications are using GLX PBuffer resources, which triggers the vulnerable code path where the XACE hook is not invoked

The system is affected if it runs a vulnerable X.Org server version (RHEL 6.0-9.0 or Fedora 39) with GLX extension enabled and SELinux/XSELINUX active, causing NULL pointer dereference when GLX PBuffer resources are accessed.

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 the vendor patch to ensure the XACE hook is called during PBuffer creation, properly labeling the buffer with a valid SID before client access is permitted.

Fix this in Fedora Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing6.0 h
  • Review / QA2.0 h
14.0 hours of engineering $2,380
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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-2024-0408 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
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