MEDIUM 5.0 GitHub
CVE-2026-55244
asteval has a Sandbox Escape via BaseException Subclasses
## Summary
An attacker who can supply expressions to `asteval.Interpreter.eval()` can raise `SystemExit`,
`KeyboardInterrupt`, `GeneratorExit`, or `BaseException` from inside the sandbox. These
exceptions are subclasses of `BaseException` but not `Exception`, so they bypass the
`except Exception:` safety net in both `run()` and `eval()`. The exception propagates
verbatim to the calling application, terminating the process or disrupting signal and
cleanup handlers.
This is distinct from prior v
Affected Products
- pip/asteval < 1.0.9
References
- https://github.com/advisories/GHSA-89v8-rhwq-hf77
- https://github.com/lmfit/asteval/security/advisories/GHSA-89v8-rhwq-hf77
- https://github.com/lmfit/asteval/pull/153
- https://github.com/lmfit/asteval/commit/a3e56e7f8ed567a4817684d94213b290359077b4
This medium severity vulnerability with a CVSS score of 5.0 was published on 2026-08-20 via GitHub. Affected: pip/asteval < 1.0.9.
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