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.

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Advisories
Source ID Title
Github GHSA Github GHSA GHSA-89v8-rhwq-hf77 asteval has a Sandbox Escape via BaseException Subclasses
Fixes

Solution

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Workaround

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History

Mon, 14 Sep 2026 21:00:00 +0000

Type Values Removed Values Added
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.
Title ASTEVAL: Sandbox Escape via BaseException Subclasses
Weaknesses CWE-248
References
Metrics cvssV3_1

{'score': 5, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:H'}


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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-09-14T20:00:24.584Z

Reserved: 2026-06-16T16:44:00.624Z

Link: CVE-2026-55244

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-09-14T20:16:47.640

Modified: 2026-09-14T20:16:47.640

Link: CVE-2026-55244

cve-icon Redhat

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cve-icon OpenCVE Enrichment

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Weaknesses