VulnerabilityDeferred

CVE-2026-55244

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…

MEDIUM 5.0EPSS 0.18%

Does this matter?

Lower severity and a low EPSS score (0.18%). Track it; it rarely justifies an emergency change on its own.

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.

CVSS 3.1: 5.0 MEDIUMCVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:H
EPSS: 0.18% probability · 7th percentile
Public exploits: None in Exploit-DB
CISA KEV: Not listed
Weakness: CWE-248
Source: security-advisories@github.com

EPSS trend

EPSS 0.2% since 26 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.

References

Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.