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BREW-checkov-CVE-2026-55244 — asteval has a Sandbox Escape via BaseException Subclasses

Affected: Homebrew: checkov

## Summary

An attacker who can supply expressions to `asteval.Interpreter.eval()` can raise `SystemExit`, `KeyboardInterrupt`, `GeneratorExit`, or `BaseException` from inside the sandbox. These exceptions are subclasses of `BaseException` but not `Exception`, so they bypass the `except Exception:` safety net in both `run()` and `eval()`. The exception propagates verbatim to the calling application, terminating the process or disrupting signal and cleanup handlers.

This is distinct from prior vulnerabilities CVE-2025-24359 (format string injection) and GHSA-vp47-9734-prjw (AST mutation TOCTOU), both fixed in 1.0.6. This vector is present in all versions including 1.0.6 and current HEAD.

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## Affected Code

**`asteval/astutils.py`, lines 89–108** — `FROM_PY` exposes dangerous classes to sandbox users:

```python FROM_PY = ('ArithmeticError', 'AssertionError', 'AttributeError', 'BaseException', # ← escapes except Exception: 'BufferError', 'BytesWarning', ... 'GeneratorExit', # ← escapes except Exception: ... 'KeyboardInterrupt', # ← escapes except Exception: ... 'SystemExit', # ← escapes except Exception: ...) ```

**`asteval/asteval.py`, line 322** — `run()` exception handler:

```python except Exception: # ← does NOT catch BaseException subclasses if with_raise and self.expr is not None: self.raise_exception…

EUVD-2026-369709

fkie_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, 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.

GHSA-89v8-rhwq-hf77 — asteval has a Sandbox Escape via BaseException Subclasses

Affected: PyPI: asteval

## Summary

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## Affected Code

**`asteval/astutils.py`, lines 89–108** — `FROM_PY` exposes dangerous classes to sandbox users:

**`asteval/asteval.py`, line 322** — `run()` exception handler:

```python except Exception: # ← does NOT catch BaseException subclasses if with_raise and self.expr is not None: self.raise_exception…

openSUSE-SU-2026:11420-1 — python313-asteval-1.0.9-1.1 on GA media

python313-asteval-1.0.9-1.1 on GA media

PYSEC-2026-3807 — asteval has a Sandbox Escape via BaseException Subclasses

Affected: PyPI: asteval

## Summary

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## Affected Code

**`asteval/astutils.py`, lines 89–108** — `FROM_PY` exposes dangerous classes to sandbox users:

**`asteval/asteval.py`, line 322** — `run()` exception handler:

```python except Exception: # ← does NOT catch BaseException subclasses if with_raise and self.expr is not None: self.raise_exception…

UBUNTU-CVE-2026-55244

Affected: Ubuntu:20.04:LTS: python-asteval, Ubuntu:22.04:LTS: python-asteval, Ubuntu:24.04:LTS: python-asteval, Ubuntu:26.04:LTS: python-asteval