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, with a CVSS score of 5.5, published 20 August 2026.
- Which products and versions are affected?
- asteval (PyPI) < 1.0.9; Lmfit < 1.0.9.
- Is there a fix for This vulnerability?
- A patch was published on 2026-06-11: Patched in version 1.0.9 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is This vulnerability attacked?
- It is attacked with local access, in a software library.
- Am I affected?
- Check whether you run asteval (PyPI) or Lmfit 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.
Technical details
The vulnerability is a sandbox escape in asteval's expression evaluator caused by two protection gaps. First, the `safe_getattr` attribute filter blocks the ctypes module itself but fails to block ctypes type objects (like `ctypes.c_long`) and their metaclass methods (`from_address`, `from_buffer`, etc.) which are reachable through numpy arrays' `.ctypes` interface without using dunder names. Second, `node_assign` (the attribute assignment handler) performs `setattr` operations with no attribute-name filtering. An attacker chains `ndarray.ctypes.shape._type_.from_address(addr)` to create a ctypes object at an arbitrary address, then uses `.value` to read (or `setattr` via unfiltered assignment to write) 8 bytes. The `id()` builtin supplies object addresses. No import statement, eval/exec, or dunder access is required. All versions of asteval < 1.0.9 with numpy installed are affected.
Affected products
- lmfit asteval < 1.0.9
Timeline
- 2026-06-11: disclosed
- 2026-06-11: patched: Patched in version 1.0.9