CVE-2017-9870
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 III_i_stereo function in layer3.c in mpglib, as used in libmpgdecoder.a in LAME 3.99.5 and other products, allows remote attackers to cause a denial of service (buffer over-read and application crash) via a crafted audio file that is mishandled in the code for the "block_type == 2" case, a similar issue to CVE-2017-11126.
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 confidenceBuffer over-read vulnerability in the III_i_stereo function in layer3.c (mpglib library, used by LAME 3.99.5) allows remote attackers to cause denial of service via a crafted audio file mishandled in the 'block_type == 2' code path.
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= 3.99.5CVSS 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
- Local
- Complexity
- Low
- Privileges
- None
- User interaction
- Required
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/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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Check if LAME is installedRun 'lame --version' or check for the lame binary/package on the systemAffected if LAME version equals exactly 3.99.5
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Check for libmpgdecoder usageInspect application dependencies or binary linking to identify if mpglib (libmpgdecoder) is in use, as this library contains the vulnerable layer3.c codeAffected if The application links against or embeds mpglib from LAME 3.99.5
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Identify applications that process untrusted MP3 filesReview which applications or services on the system handle audio file processing, particularly MP3 decodingAffected if Any application processes user-supplied or untrusted MP3 audio files
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Verify the vulnerable code path can be reachedThe vulnerability triggers specifically when processing MP3 files with block_type == 2 in the III_i_stereo function; check if the MP3 decoder handles this block typeAffected if The decoder processes MP3 files without rejecting the specific block_type == 2 condition
A system is affected only if it runs LAME version 3.99.5 or an application using the vulnerable mpglib library from that version to process MP3 audio 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 to patched versions of LAME and libmpgdecoder when available; avoid processing untrusted audio files as a defensive measure.
- Consultation2.0 h
- Implementation3.0 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 $2,800.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2017-9870 — 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-2017-9870 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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