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Out-of-bounds ReadWeakness · CWE-125

CVE-2025-49175

MEDIUM · 6.1 CVSS v3.1 Published 2025-06-17
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
63/100
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 Rendering extension's handling of animated cursors. If a client provides no cursors, the server assumes at least one is present, leading to an out-of-bounds read and potential crash.

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 X Rendering extension (X Render) where the server incorrectly assumes animated cursor data exists when a client provides no cursors, causing the server to read from invalid memory and potentially crash.

MitigationUpdate the X server implementation (e.g., X.Org Server) to properly validate cursor count before accessing cursor data, ensuring graceful handling when a client provides zero cursors.

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

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
Low
Integrity
None
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/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 server process and version
    Run 'ps aux | grep X' or 'ps aux | grep xorg' to find the X server process. Then check version with 'X -version' or check package manager: 'dpkg -l | grep xserver-xorg' (Debian) or 'rpm -qa | grep xorg-x11-server' (RHEL).
    Affected if X server version is within the affected range and no patch has been applied
  2. Verify X Render extension is loaded
    Run 'xdpyinfo -ext XRender' or check 'xwininfo -root -tree' and look for RENDER-related resources. Also check X server config: 'grep -i render /etc/X11/xorg.conf' or check /var/log/Xorg.0.log for 'RENDER' extension loading.
    Affected if X Render extension is enabled and available to clients
  3. Check for crash logs related to cursor handling
    Review X server logs: 'grep -i cursor /var/log/Xorg.0.log' or 'journalctl -b | grep -i X' for recent crashes. Also check 'dmesg' for segfaults around X session times.
    Affected if Any crashes or segfaults involving cursor or RENDER operations are found in logs
  4. Verify remote X access is enabled
    Check if X server allows remote connections: 'xhost +' shows access control. Also check 'grep -i disabled extension /var/log/Xorg.0.log'. Remote clients could trigger the malformed cursor request.
    Affected if X server has remote TCP listening enabled (not restricted to localhost)

The environment is affected if a vulnerable X server version with X Render extension is running, and a malicious or malformed client connection can trigger the zero-cursor out-of-bounds read.

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

Update the X server implementation (e.g., X.Org Server) to properly validate cursor count before accessing cursor data, ensuring graceful handling when a client provides zero cursors.

Have this fixed Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA1.0 h
10.0 hours of engineering $1,750
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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-2025-49175 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
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  • Version or environment caveats, and links to real fixes
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