CVE-2024-32646 vyper performs double eval of the slice args when buffer from adhoc locations
Vyper compiler double-evaluates slice arguments with side effects, potentially allowing unintended code execution in smart contracts.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2024-32646?
CVE-2024-32646 is a medium-severity code injection vulnerability in vyperlang vyper, published on 25 Apr 2024. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Vyper 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.
Weakness: CWE-20
Which versions are affected by CVE-2024-32646?
3 open source packages ship an affected version, including vyper. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
vyper PyPI | All versions | 0.4.0 |
vyper PyPI | All versions | 0.4.0 |
vyper PyPI | All versions | 0.4.0 |
Products include Vyperlang Vyper.
How do I fix CVE-2024-32646?
Upgrade vyper to 0.4.0 or later.
Upgrade, and never evaluate templates, expressions or code built from user input. More about Code injection.
Is CVE-2024-32646 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2024-32646 exists.
Other vulnerabilities in vyperlang vyper
- CVE-2024-24563 Vyper array negative index vulnerability
- CVE-2024-24561 Vyper bounds check on built-in `slice()` function can be overflowed
- CVE-2023-39363 Vyper incorrectly allocated named re-entrancy locks
- CVE-2022-24845 Integer bounds error in Vyper
- CVE-2022-29255 Multiple evaluation of contract address in call in vyper
Sources
Also known as GHSA-r56x-j438-vw5m, PYSEC-2024-207.