CVE-2024-32648: vyper default functions don't respect nonreentrancy keys
First published: Thu Apr 25 2024(Updated: )
### Summary Prior to v0.3.0, `__default__()` functions did not respect the `@nonreentrancy` decorator and the lock was not emitted. This is a known bug and was already visible in the issue tracker (https://github.com/vyperlang/vyper/issues/2455), but it is being re-issued as an advisory so that tools relying on the advisory publication list can incorporate it into their searches. A contract search was additionally performed and no vulnerable contracts were found in production. ### PoC ```vyper @external @payable @nonreentrant("default") def __default__(): pass ``` after codegen: ``` [seq, [if, [lt, calldatasize, 4], [goto, fallback]], [mstore, 28, [calldataload, 0]], [with, _func_sig, [mload, 0], seq], [seq_unchecked, [label, fallback], [seq, pass, # Line 5 pass, pass, # Line 4 stop]]], ``` ### Impact No vulnerable production contracts were found. Additionally, using a lock on a `default` function is a very sparsely used pattern. As such, the impact is `low`.
Credit: security-advisories@github.com security-advisories@github.com
| Affected Software | Affected Version | How to fix |
|---|---|---|
| pip/vyper | <=0.2.16 | 0.3.0 |
| Vyper | <0.3.0 |
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Reference Links
- https://github.com/vyperlang/vyper/commit/93287e5ac184b53b395c907d40701f721daf8177
- https://github.com/vyperlang/vyper/issues/2455
- https://github.com/vyperlang/vyper/security/advisories/GHSA-m2v9-w374-5hj9
- https://nvd.nist.gov/vuln/detail/CVE-2024-32648
- https://github.com/advisories/GHSA-m2v9-w374-5hj9 (Advisory)
- https://github.com/pypa/advisory-database/tree/main/vulns/vyper/PYSEC-2024-163.yaml
Frequently Asked Questions
What is the severity of CVE-2024-32648?
CVE-2024-32648 is considered a significant bug as it affects the security and proper functionality of the Vyper programming language by not properly implementing the `@nonreentrancy` decorator.
How do I fix CVE-2024-32648?
To fix CVE-2024-32648, upgrade to Vyper version 0.3.0 or later.
Which versions are affected by CVE-2024-32648?
CVE-2024-32648 affects Vyper versions prior to 0.3.0, including 0.2.16 and earlier.
What is the main issue with CVE-2024-32648?
The main issue with CVE-2024-32648 is that the `__default__()` functions do not respect the `@nonreentrancy` decorator, failing to emit the necessary lock.
Where can I find more information about CVE-2024-32648?
More information about CVE-2024-32648 can be found in the issue tracker on GitHub where the bug was documented.
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