CVE-2011-3941
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 · uneditedThe decode_mb function in libavcodec/error_resilience.c in FFmpeg before 0.10 allows remote attackers to have an unspecified impact via vectors related to an uninitialized block index, which triggers an out-of-bounds write.
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 confidenceOut-of-bounds write vulnerability in FFmpeg's libavcodec/error_resilience.c decode_mb function, caused by an uninitialized block index variable. The uninitialized value leads to memory corruption when the function attempts to write to an out-of-bounds memory location, potentially allowing remote code execution or denial of service when processing specially crafted video streams.
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<= 0.9.1= 0.3= 0.3.1= 0.3.2= 0.3.3= 0.3.4= 0.4.0= 0.4.2= 0.4.3= 0.4.4= 0.4.5= 0.4.6CVSS 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
- Authentication
- None
- Confidentiality
- Partial
- Integrity
- Partial
- Availability
- Partial
AV:N/AC:L/Au:N/C:P/I:P/A:P
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 checksWork through these to decide whether this CVE applies to you.
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Confirm FFmpeg is installedRun `ffmpeg -version` or check for libavcodec library files on the systemAffected if FFmpeg or its libavcodec library is present on the system
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Identify the installed FFmpeg versionExecute `ffmpeg -version` and note the version number in the output, or query the libavcodec library version if using a packaged versionAffected if The displayed version matches any of: 0.3, 0.3.1, 0.3.2, 0.3.3, 0.3.4, 0.4.0, 0.4.2, 0.4.3, 0.4.4, 0.4.5, 0.4.6, or any version 0.9.1 or earlier
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Verify the libavcodec component existsCheck for the presence of libavcodec library files (libavcodec.so on Linux, avcodec.dll on Windows, or similar) which contain the error_resilience.c moduleAffected if The libavcodec library is present, as the vulnerability resides in the decode_mb function within this component
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Confirm video processing capability is in useReview whether the system processes video streams using FFmpeg tools or applications that link to libavcodec, as the flaw is triggered during decode_mb execution when processing crafted video streamsAffected if Applications or scripts process video files using FFmpeg libraries
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Compare version against vulnerability rangeCross-reference the installed version against the known affected versions: <= 0.9.1, or any of 0.3.x (0.3 through 0.3.4) or 0.4.x (0.4.0, 0.4.2 through 0.4.6)Affected if The installed version falls within any of these specific affected version ranges
The system is likely affected if FFmpeg or libavcodec is installed and the version matches 0.3.x, 0.4.x (excluding 0.4.1), or any version 0.9.1 or earlier.
Generated from the published advisory. Verify against your own configuration.
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 dataUpdate FFmpeg to version 0.10 or later to obtain the patched library. No configuration-based workaround exists; the vulnerability requires a code-level fix through library update.
- Consultation2.0 h
- Implementation4.0 h
- Testing4.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2011-3941 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2011-3941 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- 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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