CVE-2018-9841
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 export function in libavfilter/vf_signature.c in FFmpeg through 3.4.2 allows remote attackers to cause a denial of service (out-of-array access) or possibly have unspecified other impact via a long filename.
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 confidenceA buffer overflow vulnerability exists in the export function of libavfilter/vf_signature.c in FFmpeg through version 3.4.2. The vulnerability is triggered by providing an excessively long filename to the signature export function, causing an out-of-array access that can lead to denial of service or potentially allow arbitrary code execution.
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<= 3.4.2CVSS 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
- Privileges
- None
- User interaction
- Required
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/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 checksWork through these to decide whether this CVE applies to you.
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Determine FFmpeg versionRun 'ffmpeg -version' or 'ffmpeg -buildconf' to display the version numberAffected if Version is 3.4.2 or lower
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Verify signature filter is availableRun 'ffmpeg -filters 2>/dev/null | grep signature' to check if the signature filter is compiled inAffected if The signature filter appears in the available filters list
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Check for signature export usageReview command-line arguments or configuration for '-export_signature' or similar export parameters used with the signature filterAffected if The signature export functionality is being invoked with user-controlled filenames
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Inspect libavfilter libraryCheck for presence of libavfilter.so or libavfilter.dll and verify it was built from a version <= 3.4.2Affected if The linked libavfilter library version is 3.4.2 or earlier
A user is affected if they are running FFmpeg version 3.4.2 or earlier and using the signature export filter with untrusted or excessively long filenames as input.
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 dataUpgrade FFmpeg to version 3.4.3 or later which contains the patch fixing the out-of-bounds access in vf_signature.c.
- Consultation2.0 h
- Implementation2.0 h
- Testing4.0 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 $2,752.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2018-9841 — 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-2018-9841 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
- No spam, self-promotion, credentials, or personal data