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CVE-2026-55244— ASTEVAL: Sandbox Escape via BaseException Subclasses

Quick assessment

Affected
lmfit asteval
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

asteval 是一个用于评估 Python 表达式和语句的库。在 1.0.9 版本之前， 中的 将 、 、 和 暴露给由 评估的表达式；而 中的 和 捕获的是 ，而非这些非 的 子类。当攻击者控制的表达式抛出上述异常类之一时， 会将该异常类传递给 ，导致生成的异常绕过解释器的安全处理器，并传播到调用该库的应用程序中。因此，评估不可信表达式的消费服务可能被终止，或其信号和清理处理被打乱，从而导致服务拒绝（DoS）。此处单独记录的只读 功能不属于此漏洞范围。该问题已在 1.0.9 版本中修复。

CVSS 5.0 · Medium

Possible ATT&CK Techniques 1 AI

T1499 · Endpoint Denial of Service
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I. Basic Information for CVE-2026-55244

Vulnerability Information
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Vulnerability Title
ASTEVAL: Sandbox Escape via BaseException Subclasses
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
未捕获的异常
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
lmfit asteval < 1.0.9 -

II. Public POCs for CVE-2026-55244

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III. Intelligence Information for CVE-2026-55244

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Patches & Fixes for CVE-2026-55244 (3)

Vendor Advisories for CVE-2026-55244 (1)

Vendor Pages for CVE-2026-55244 (1)

IV. Related Vulnerabilities

Same product: asteval
Same vendor: lmfit
Same weakness: CWE-248

V. Comments for CVE-2026-55244

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