Ubuntu LinuxOperating system · Canonical
CVE-2015-6818
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_ihdr_chunk function in libavcodec/pngdec.c in FFmpeg before 2.7.2 does not enforce uniqueness of the IHDR (aka image header) chunk in a PNG image, which allows remote attackers to cause a denial of service (out-of-bounds array access) or possibly have unspecified other impact via a crafted image with two or more of these chunks.
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 decode_ihdr_chunk function in FFmpeg's PNG decoder (libavcodec/pngdec.c) before version 2.7.2 fails to enforce uniqueness of the IHDR chunk, allowing multiple IHDR chunks in a single PNG file. This leads to out-of-bounds array access when the decoder processes a crafted image containing two or more IHDR chunks.
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
Ubuntu LinuxOperating system
= 12.04<= 2.7.1CVSS 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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Check if FFmpeg is installedRun `ffmpeg -version` or `avconv -version` to determine if FFmpeg (or its fork avconv) is present on the system.Affected if FFmpeg is installed and the version displayed is 2.7.1 or earlier.
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Identify the exact FFmpeg versionExecute `ffmpeg -version 2>&1 | head -1` or `avconv -version 2>&1 | head -1` and note the full version string (e.g., 2.7.1, 2.6.x, 2.5.x, etc.).Affected if The version number is 2.7.1 or lower.
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Verify PNG decoding support is compiled inRun `ffmpeg -codecs 2>&1 | grep -i png` or check if libavcodec/pngdec.c is in use by running `ffmpeg -formats 2>&1 | grep -i png`.Affected if PNG demuxer and decoder are listed as available (image processing with FFmpeg is possible).
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Confirm the vulnerable code path existsCheck the FFmpeg binary or library for the presence of the pngdec component. On Debian/Ubuntu, inspect the package: `dpkg -l | grep -i ffmpeg` or `dpkg -l | grep -i libav`.Affected if The installed package version corresponds to FFmpeg <= 2.7.1 and includes PNG support.
The system is affected if FFmpeg (or avconv from libav) version 2.7.1 or earlier is installed and PNG decoding capability is enabled, allowing crafted PNG files with multiple IHDR chunks to trigger out-of-bounds access.
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 2.7.2 or later. Alternatively, sanitize or validate PNG files before processing to ensure they contain only a single IHDR chunk.
Fix this in Ubuntu Linux
Scoped from the published advisory
- 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-2015-6818 — 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-2015-6818 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
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