CVE-2024-32648: vyper default functions don't respect nonreentrancy keys
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, funcsig, [mload, 0], seq], [sequnchecked, [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.
Other sources
Vyper is a pythonic Smart Contract Language for the Ethereum virtual machine. Prior to version 0.3.0, default functions don't respect nonreentrancy keys and the lock isn't emitted. 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. Version 0.3.0 contains a patch for the issue.
— MITRE
Affected Software
Remediation
Event History
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.