Out-of-bounds Write Affecting vyper package, versions [0.1.0b4, 0.3.0)
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
Do your applications use this vulnerable package?
In a few clicks we can analyze your entire application and see what components are vulnerable in your application, and suggest you quick fixes.
Test your applications- Snyk IDSNYK-PYTHON-VYPER-22132609
- published2 Nov 2026
- disclosed21 Oct 2026
- creditUnknown
Introduced: 21 Oct 2026
NewCVE-2021-48020 (opens in a new tab)How to fix?
Upgrade vyper to version 0.3.0 or higher.
Overview
vyper is a Pythonic Smart Contract Language for the EVM.
Affected versions of this package are vulnerable to Out-of-bounds Write via nested internal function calls within list and tuple expressions in parse_List and parse_Tuple in vyper/parser/expr.py. When a list or tuple literal contains internal function calls as elements, the compiler fails to evaluate and store those call results to memory before constructing the multi-value LLL node, allowing the call return data to corrupt adjacent memory regions in the compiled contract. This can result in incorrect contract behavior and storage integrity violations at runtime.