CVE-2025-9959: Sandbox escape in smolagents Local Python execution environment via dunder attributes

Severity: high (CVSS 7.6 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-09-03 · updated 2026-09-26
Weakness: CWE-94

Description

Incomplete validation of dunder attributes allows an attacker to escape from the Local Python execution environment sandbox, enforced by smolagents. The attack requires a Prompt Injection in order to trick the agent to create malicious code.

References

https://github.com/huggingface/smolagents/pull/1551
https://research.jfrog.com/vulnerabilities/smolagents-local-python-sandbox-escape-jfsa-2025-001434277/

Get alerted when CVE-2025-9959 or the next vulnerability affects your stack