Quick answers
- Is This vulnerability exploited in the wild?
- No. Junglewise Threat Intelligence has no report of This vulnerability being exploited in the wild.
- How severe is This vulnerability?
- Medium severity, published 6 October 2026.
- Which products and versions are affected?
- vyper (PyPI) >= 0.1.0b10, < 0.2.3; Vyper before 0.2.3.
- Is there a fix for This vulnerability?
- Yes: fixed in Vyper 0.2.3. Until then: Avoid placing return statements inside for loops in internal functions that are called from other internal functions; instead, move the return statement outside the loop. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is This vulnerability attacked?
- It is attacked over the network, in a software library.
- Am I affected?
- Check whether you run vyper (PyPI) or Vyper at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
How to fix
- Fixed in: Vyper 0.2.3
Avoid placing return statements inside for loops in internal functions that are called from other internal functions; instead, move the return statement outside the loop.
Technical details
The vulnerability occurs when a return statement is placed inside a for loop that is part of a nested internal function call chain (2+ levels deep), resulting in an invalid jump destination that causes a stack underflow. The issue affects code patterns where internal functions call other internal functions that contain return statements in loops. A fix exists in Vyper 0.2.3 and was patched in PR #2110.
Affected products
- Vyper Vyper before 0.2.3
Timeline
- 2026-10-06: disclosed
- 2026-10-06: patched: Fixed in Vyper 0.2.3 via PR #2110