CVE-2011-3940
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 · uneditednsvdec.c in libavcodec in FFmpeg 0.7.x before 0.7.12 and 0.8.x before 0.8.11, and in Libav 0.5.x before 0.5.9, 0.6.x before 0.6.6, 0.7.x before 0.7.5, and 0.8.x before 0.8.1, allows remote attackers to cause a denial of service (out-of-bounds read and write) via a crafted NSV file that triggers "use of uninitialized streams."
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 confidenceThe vulnerability exists in nsvdec.c, the NSV (NullSoft Video) decoder in libavcodec. A crafted NSV file with uninitialized streams causes the decoder to perform out-of-bounds memory read and write operations, leading to denial of service. The root cause is improper handling of uninitialized stream data during file parsing.
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= 0.7.1= 0.7.2= 0.7.6= 0.7.7= 0.7.8= 0.7.9= 0.7.11= 0.8.5= 0.8.6= 0.8.7= 0.8.8= 0.8.10= 0.5= 0.5.1= 0.5.2= 0.5.3= 0.5.4= 0.5.5= 0.5.6= 0.5.7= 0.6= 0.6.1= 0.6.2= 0.6.3CVSS 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
- M
- Authentication
- None
- Confidentiality
- Partial
- Integrity
- Partial
- Availability
- Partial
AV:N/AC:M/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.
-
Identify installed FFmpeg versionRun 'ffmpeg -version' or 'ffmpeg -version | head -1' to get the version numberAffected if Version matches 0.7.1, 0.7.2, 0.7.6, 0.7.7, 0.7.8, 0.7.9, 0.7.11, 0.8.5, 0.8.6, 0.8.7, 0.8.8, or 0.8.10
-
Identify installed Libav versionRun 'avconv -version' or 'libavutil-version' to get the Libav version numberAffected if Version matches any release from 0.5.x through 0.6.3, or equals 0.7, 0.7.1, 0.7.2, 0.7.3, 0.7.4, 0.8, or 0.8.0
-
Check for libavcodec dependencyRun 'ldd <executable>' or check package dependencies for tools using libavcodec such as video players or transcodersAffected if The application links against a vulnerable libavcodec library version from the affected ranges above
-
Verify NSV decoding capability existsRun 'ffmpeg -formats 2>/dev/null | grep -i nsv' or check if nsvdec.c is compiled into the libraryAffected if NSV format support is compiled into the library, which is the default configuration in affected versions
You are affected if you have FFmpeg 0.7.x/0.8.x or Libav 0.5.x-0.6.3 installed and use them to process NSV files.
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 0.7.12+/0.8.11+ or Libav to 0.5.9+/0.6.6+/0.7.5+/0.8.1+. As a defense-in-depth measure, implement validation of NSV file headers and stream initialization before passing files to the decoder.
- Consultation2.0 h
- Implementation4.0 h
- Testing3.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,088.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2011-3940 — 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-2011-3940 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
Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.
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.
- 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