PythonApplication
CVE-2017-18207
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 Wave_read._read_fmt_chunk function in Lib/wave.py in Python through 3.6.4 does not ensure a nonzero channel value, which allows attackers to cause a denial of service (divide-by-zero and exception) via a crafted wav format audio file. NOTE: the vendor disputes this issue because Python applications "need to be prepared to handle a wide variety of exceptions.
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 confidenceThe Wave_read._read_fmt_chunk function in Python's Lib/wave.py library fails to validate that the channel count in a WAV file header is nonzero. When processing a crafted WAV file with zero channels, this leads to a divide-by-zero exception during audio parameter calculations, causing denial of service.
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
PythonApplication
<= 3.6.4CVSS 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
- None
- Integrity
- None
- Availability
- High
CVSS:3.0/AV:N/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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Identify Python versionRun 'python --version' or 'python3 --version' to get the installed Python versionAffected if Version is 3.6.4 or earlier (any version <= 3.6.4)
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Locate wave.py moduleRun 'python -c "import wave; print(wave.__file__)"' to find the wave.py file in useAffected if The module is found in Python's Lib directory (not a patched third-party version)
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Inspect wave.py for channel validationOpen the wave.py file and search for the _read_fmt_chunk function; check if there is a validation check for nchannels being nonzero (the fix adds 'if nchannels <= 0: raise wave.Error("bad # of channels")')Affected if The validation check is absent; the code proceeds directly to calculations using nchannels without checking if it is zero
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Identify WAV file processingSearch application code for imports of 'wave' module and usage of wave.open() or wave.Wave_read to process WAV filesAffected if The application uses wave module to open and process WAV files from any source
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Assess input trustReview whether the application accepts WAV files from untrusted sources such as user uploads, network requests, or external inputAffected if The application processes WAV files from untrusted or external sources without prior validation
If Python version is 3.6.4 or earlier AND the application uses the wave module to process WAV files from untrusted sources AND wave.py lacks channel count validation, the environment is affected by this CVE.
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 dataValidate WAV file channel counts before processing or update Python to a version with bounds checking in wave.py; applications should handle exceptions from untrusted audio input.
Fix this in Python
Scoped from the published advisory
- Consultation2.0 h
- Implementation1.0 h
- Testing2.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,696.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2017-18207 — 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-2017-18207 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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- Version or environment caveats, and links to real fixes
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