{"id":"CVE-2026-55244","summary":"ASTEVAL: Sandbox Escape via BaseException Subclasses","details":"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.","aliases":["GHSA-89v8-rhwq-hf77","PYSEC-2026-3807"],"modified":"2026-09-18T03:30:38.699219336Z","published":"2026-09-14T20:00:24.584Z","related":["openSUSE-SU-2026:11420-1"],"database_specific":{"cwe_ids":["CWE-248"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/55xxx/CVE-2026-55244.json","cna_assigner":"GitHub_M"},"references":[{"type":"WEB","url":"https://github.com/lmfit/asteval/releases/tag/1.0.9"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/55xxx/CVE-2026-55244.json"},{"type":"ADVISORY","url":"https://github.com/lmfit/asteval/security/advisories/GHSA-89v8-rhwq-hf77"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-55244"},{"type":"FIX","url":"https://github.com/lmfit/asteval/commit/9c625b3674f8d05f206708bb85afca17a87694a4"},{"type":"FIX","url":"https://github.com/lmfit/asteval/commit/c49c99a67acb63eb7410231932250bd820380e45"},{"type":"FIX","url":"https://github.com/lmfit/asteval/pull/153"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/lmfit/asteval","events":[{"introduced":"0"},{"fixed":"9c625b3674f8d05f206708bb85afca17a87694a4"},{"fixed":"c49c99a67acb63eb7410231932250bd820380e45"},{"fixed":"0b359d0b03195d1288af656e98730ab691b04f5a"}],"database_specific":{"extracted_events":[{"introduced":"0"},{"fixed":"1.0.9"}],"source":["AFFECTED_FIELD","REFERENCES"]}}],"versions":["1.0.8","1.0.7","1.0.6","1.0.5","1.0.4","1.0.3","1.0.2","1.0.1","1.0.0","0.9.33","0.9.32","0.9.31","0.9.30","0.9.29","0.9.28","0.9.27","0.9.26","0.9.25","0.9.24","0.9.23","0.9.22","0.9.21","0.9.20","0.9.19","0.9.18","0.9.17","0.9.16","0.9.15","0.9.14","0.9.13","0.9.12","0.9.11","0.9.10","0.9.9","0.9.7","0.9.6","0.9.5","0.9.4","0.9.3.1","0.9.3","0.9.2","0.9.1","0.9"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-55244.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:H"}]}