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, SystemEx…
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.
Why it matters
- ▸ Requires local access, limiting mass exploitation
- ▸ Low attack complexity — no special conditions needed to exploit
- ▸ Requires low-privilege access first
- ▸ Requires the victim to take an action (e.g. open a file or link)
Apply the vendor patch as soon as it's available or already released. Review and restrict accounts with the privilege level this vulnerability requires. User-awareness training reduces risk here, since exploitation depends on tricking a user into acting.
This analysis is generated from structured CVSS vector data, CISA KEV cross-referencing, and vendor/product category rules — not a manual expert review. Treat it as a starting point, not a substitute for your own assessment.
CVSS Vector Breakdown
EU Vulnerability Database (ENISA)
EUVD is ENISA's EU vulnerability database, still in beta. EPSS is a probabilistic exploitation-likelihood score, not a certainty.
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