VyperApplication · Vyperlang
CVE-2024-32646
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 · uneditedVyper is a pythonic Smart Contract Language for the Ethereum virtual machine. In versions 0.3.10 and prior, using the `slice` builtin can result in a double eval vulnerability when the buffer argument is either `msg.data`, `self.code` or `<address>.code` and either the `start` or `length` arguments have side-effects. It can be easily triggered only with the versions `<0.3.4` as `0.3.4` introduced the unique symbol fence. No vulnerable production contracts were found. Additionally, double evaluation of side-effects should be easily discoverable in client tests. As such, the impact is low. As of time of publication, no fixed versions are available.
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 confidenceIn Vyper smart contract language versions 0.3.10 and prior, the `slice` builtin function contains a double evaluation vulnerability. When the buffer argument is `msg.data`, `self.code`, or `<address>.code` and either the `start` or `length` arguments contain side-effects, those side-effects are evaluated twice instead of once. This was partially mitigated in version 0.3.4 with a unique symbol fence, making exploitation easier only in versions prior to 0.3.4.
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
VyperApplication
< 0.4.0CVSS 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
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- Low
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
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 the Vyper compiler versionRun 'vyper --version' or check the version in your build system/dependency lock fileAffected if The version is below 0.4.0 (particularly 0.3.10 or prior, or below 0.3.4 for easier exploitation)
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Identify slice usage with msg.data, self.code, or address.codeSearch your Vyper contract source code for slice() calls where the first argument is 'msg.data', 'self.code', or any '<address>.code' expressionAffected if Your contract uses slice with one of these buffer types as the first argument
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Inspect slice start and length arguments for side-effectsReview the second (start) and third (length) arguments in any slice calls with vulnerable buffers. Look for function calls, external contract interactions, or state modifications in these argumentsAffected if The start or length arguments contain side-effects such as function calls, storage writes, or external calls
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Determine if the double evaluation can occur in your contextIf you have slice with msg.data/self.code/<address>.code as buffer AND start/length have side-effects, the double evaluation will occur. Versions prior to 0.3.4 are more easily exploitable due to missing symbol fence mitigationAffected if All three conditions are met: vulnerable buffer type, side-effects in start/length, and Vyper version below 0.4.0
You are affected if you are using Vyper below version 0.4.0 AND your contracts contain slice() calls with msg.data, self.code, or <address>.code as the buffer where the start or length arguments contain side-effects.
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 data0.4.0
Avoid using `slice` with `msg.data`, `self.code`, or `<address>.code` buffers when the `start` or `length` arguments have side-effects; conduct thorough testing to verify no double evaluation occurs in contracts; monitor for patched versions of Vyper and upgrade promptly.
Fix this in Vyper
Scoped from the published advisory
- Consultation2.0 h
- Implementation1.0 h
- Testing4.0 h
- Review / QA1.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2024-32646 — 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-2024-32646 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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