CVE-2026-102734 asteval sandbox escape: arbitrary native memory read/write via numpy ctypes in default asteval Interpreter
Attackers can escape the asteval sandbox to read/write arbitrary memory and execute code via numpy ctypes in the default interpreter.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-102734?
CVE-2026-102734 is a medium-severity code injection vulnerability in lmfit asteval, published on 13 Oct 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
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.
Which versions are affected by CVE-2026-102734?
2 open source packages ship an affected version, including asteval.
| Package | Affected | Fixed in |
|---|---|---|
asteval PyPI | All versions | 1.0.9 |
asteval PyPI | All versions | 1.0.9 |
How do I fix CVE-2026-102734?
Upgrade asteval to 1.0.9 or later.
Upgrade, and never evaluate templates, expressions or code built from user input. More about Code injection.
Is CVE-2026-102734 being exploited?
There is no known exploitation of CVE-2026-102734 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-102734, GHSA-9w56-46f6-3qhx, UBUNTU-CVE-2026-102734.