CVE-2026-55244
ASTEVAL is an evaluator of Python expressions and statements. Prior to 1.0.9, FROM_PY in asteval/astutils.py exposes BaseException, SystemExit, KeyboardInterrupt, and GeneratorExit to expressions evaluated by asteval.Interpreter.eval(), while run() and eval() in asteval/asteval.py catch Exception rather than these non-Exception BaseException subclasses. When an attacker-controlled expression raises one of these classes, on_raise() passes the class to raise_exception(), and the resulting exception bypasses the interpreter's safety handlers and propagates into the calling application. A consuming service that evaluates untrusted expressions can therefore be terminated or have signal and cleanup handling disrupted, causing denial of service. The separately documented read-only open() capability is not part of this vulnerability. This issue is fixed in version 1.0.9.
- CVSS 3.1
- 5.0
CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:H - EPSS
- 0.2% chance of exploitation in the next 30 days; higher than 7% of CVEs (scores of 2026-10-25)
- CWE
- CWE-248
- Published
- Modified
- Record from
- the NVD, synced
Packages (OSV)
| Advisory | Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|---|
| GHSA-89v8-rhwq-hf77 | PyPI | asteval | <1.0.9 | 1.0.9 |
| PYSEC-2026-3807 | PyPI | asteval | <1.0.9 | 1.0.9 |
References
- https://github.com/lmfit/asteval/commit/9c625b3674f8d05f206708bb85afca17a87694a4
- https://github.com/lmfit/asteval/commit/c49c99a67acb63eb7410231932250bd820380e45
- https://github.com/lmfit/asteval/pull/153
- https://github.com/lmfit/asteval/releases/tag/1.0.9
- https://github.com/lmfit/asteval/security/advisories/GHSA-89v8-rhwq-hf77