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Heap-based Buffer OverflowWeakness · CWE-122

CVE-2025-9951

HIGH · 7.2 CVSS v4.0 Published 2025-09-09
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
78/100
Remediation priority · High
Remotely reachable 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 heap-buffer-overflow write exists in jpeg2000dec FFmpeg which allows an attacker to potentially gain remote code execution or cause denial of service via the channel definition cdef atom of JPEG2000.

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 · moderate confidence

A heap-buffer-overflow write vulnerability exists in the jpeg2000dec component of FFmpeg. The flaw is triggered when processing the channel definition cdef atom within JPEG2000 image files, allowing an attacker to write data beyond allocated buffer boundaries.

MitigationUpdate FFmpeg to the latest version containing the security fix for CVE-2025-9951. Until patched, avoid processing untrusted JPEG2000 files with FFmpeg tools.

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
Network
Complexity
High
Privileges
Low
Authentication
X
User interaction
None
Scope
X

CVSS:4.0/AV:N/AC:H/AT:N/PR:L/UI:N/VC:N/VI:H/VA:H/SC:N/SI:H/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

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 FFmpeg is installed
    Run 'ffmpeg -version' or 'which ffmpeg' to confirm FFmpeg is present on the system
    Affected if FFmpeg is not installed - the system is not vulnerable to this specific flaw
  2. Determine installed FFmpeg version
    Execute 'ffmpeg -version' and capture the version number from the output
    Affected if The installed version falls within the range of affected versions that contain the vulnerable jpeg2000dec code
  3. Confirm jpeg2000 decoding support is enabled
    Run 'ffmpeg -codecs 2>/dev/null | grep -i jpeg2000' or 'ffmpeg -formats 2>/dev/null | grep -i jp2' to check if JPEG2000 decoding is available
    Affected if JPEG2000 decoding is enabled and available - the vulnerable code path can be triggered
  4. Identify if untrusted JPEG2000 files are processed
    Review application logs, file processing workflows, or user activity that involves decoding JPEG2000 images using FFmpeg
    Affected if The system processes or decodes JPEG2000 image files from untrusted sources using FFmpeg tools

The environment is affected if FFmpeg with an unpatched version containing the vulnerable jpeg2000dec component is installed and processes JPEG2000 files containing a maliciously crafted cdef atom.

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 FFmpeg to the latest version containing the security fix for CVE-2025-9951. Until patched, avoid processing untrusted JPEG2000 files with FFmpeg tools.

Have this fixed Scoped from the published advisory
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing4.0 h
  • Review / QA2.0 h
15.0 hours of engineering $2,640
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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-2025-9951 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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