{"id":"CVE-2026-55244","state":"PUBLISHED","title":"ASTEVAL: Sandbox Escape via BaseException Subclasses","description":"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.","publishedAt":"2026-09-14T20:00:24.584Z","updatedAt":"2026-09-16T16:17:50.777Z","severity":{"score":5,"label":"Medium","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:H","source":"GitHub_M"},"assigner":"GitHub_M","products":["lmfit asteval"],"affected":[{"vendor":"lmfit","product":"asteval","versions":[{"version":"< 1.0.9","status":"affected"}]}],"references":["https://github.com/lmfit/asteval/security/advisories/GHSA-89v8-rhwq-hf77","https://github.com/lmfit/asteval/pull/153","https://github.com/lmfit/asteval/commit/9c625b3674f8d05f206708bb85afca17a87694a4","https://github.com/lmfit/asteval/commit/c49c99a67acb63eb7410231932250bd820380e45","https://github.com/lmfit/asteval/releases/tag/1.0.9"],"weaknesses":["CWE-248"],"ingestedAt":"2026-10-29T20:12:24.861Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/55xxx/CVE-2026-55244.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-55244","state":"PUBLISHED","datePublished":"2026-09-14T20:00:24.584Z","dateUpdated":"2026-09-16T16:17:50.777Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-06-16T16:44:00.624Z"},"containers":{"cna":{"title":"ASTEVAL: Sandbox Escape via BaseException Subclasses","descriptions":[{"lang":"en","value":"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."}],"affected":[{"vendor":"lmfit","product":"asteval","versions":[{"version":"< 1.0.9","status":"affected"}]}],"references":[{"url":"https://github.com/lmfit/asteval/security/advisories/GHSA-89v8-rhwq-hf77","name":"https://github.com/lmfit/asteval/security/advisories/GHSA-89v8-rhwq-hf77","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/lmfit/asteval/pull/153","name":"https://github.com/lmfit/asteval/pull/153","tags":["x_refsource_MISC"]},{"url":"https://github.com/lmfit/asteval/commit/9c625b3674f8d05f206708bb85afca17a87694a4","name":"https://github.com/lmfit/asteval/commit/9c625b3674f8d05f206708bb85afca17a87694a4","tags":["x_refsource_MISC"]},{"url":"https://github.com/lmfit/asteval/commit/c49c99a67acb63eb7410231932250bd820380e45","name":"https://github.com/lmfit/asteval/commit/c49c99a67acb63eb7410231932250bd820380e45","tags":["x_refsource_MISC"]},{"url":"https://github.com/lmfit/asteval/releases/tag/1.0.9","name":"https://github.com/lmfit/asteval/releases/tag/1.0.9","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"LOCAL","availabilityImpact":"HIGH","baseScore":5,"baseSeverity":"MEDIUM","confidentialityImpact":"NONE","integrityImpact":"NONE","privilegesRequired":"LOW","scope":"UNCHANGED","userInteraction":"REQUIRED","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:H","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-248","lang":"en","description":"CWE-248: Uncaught Exception","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-09-14T20:00:24.584Z"},"source":{"advisory":"GHSA-89v8-rhwq-hf77","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","references":[{"url":"https://github.com/lmfit/asteval/security/advisories/GHSA-89v8-rhwq-hf77","tags":["exploit"]}],"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-09-16T16:17:25.234532Z","id":"CVE-2026-55244","options":[{"Exploitation":"poc"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-09-16T16:17:50.777Z"}}]}}}