Vulnerability · Published Oct 13, 2026 · Assigned by GitHub_M

CVE-2026-102734asteval sandbox escape: arbitrary native memory read/write via numpy ctypes in default asteval Interpreter

Medium 5.5

In plain English

A medium-severity security flaw in asteval from lmfit. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.1% (higher than 2% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)5.5Medium

Exploit odds (30 days)0.1%top 97.7% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

asteval is a Python expression evaluator designed for restricted execution. Prior to 1.0.9, in asteval/astutils.py, the default Interpreter with numpy enabled exposes a ctypes type and permits from_address memory access. safe_getattr blocks the ctypes module but not reachable ctypes type objects, while attribute assignments use unfiltered setattr instead of safe_setattr. An attacker-controlled expression can derive an address with id, read memory through from_address, and write through an attribute assignment. The expression can read or corrupt arbitrary process memory, escape the intended sandbox, execute code, disclose secrets, or crash the host process. This issue is fixed in version 1.0.9.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Debian:12	python-asteval	no fix listed	DEBIAN-CVE-2026-102734
Debian:13	python-asteval	no fix listed	DEBIAN-CVE-2026-102734
Debian:14	python-asteval	no fix listed	DEBIAN-CVE-2026-102734
PyPI	asteval	1.0.9	GHSA-9w56-46f6-3qhx
Ubuntu:22.04:LTS	python-asteval	no fix listed	UBUNTU-CVE-2026-102734
Ubuntu:24.04:LTS	python-asteval	no fix listed	UBUNTU-CVE-2026-102734
Ubuntu:26.04:LTS	python-asteval	no fix listed	UBUNTU-CVE-2026-102734
Ubuntu:26.10	python-asteval	no fix listed	UBUNTU-CVE-2026-102734

Affected products (as reported)

Vendor	Product	Versions
lmfit	asteval	< 1.0.9

Weakness: CWE-693, CWE-749, CWE-913 · Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

References

https://github.com/lmfit/asteval/security/advisories/GHSA-9w56-46f6-3qhx x_refsource_CONFIRM
https://github.com/lmfit/asteval/pull/153 x_refsource_MISC
https://github.com/lmfit/asteval/commit/a3e56e7f8ed567a4817684d94213b290359077b4 x_refsource_MISC
https://github.com/lmfit/asteval/releases/tag/1.0.9 x_refsource_MISC