CVE-2026-4963 huggingface smolagents Incomplete Fix CVE-2025-9959 local_python_executor.py evaluate_with code injection

What is CVE-2026-4963?

CVE-2026-4963 is a medium-severity code injection vulnerability in huggingface smolagents, published on 27 Mar 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

Official description

A weakness has been identified in huggingface smolagents 1.25.0.dev0. This affects the function evaluate_augassign/evaluate_call/evaluate_with of the file src/smolagents/local_python_executor.py of the component Incomplete Fix CVE-2025-9959. This manipulation causes code injection. It is possible to initiate the attack remotely. The exploit has been made available to the public and could be used for attacks. The vendor was contacted early about this disclosure but did not respond in any way.

Weakness: CWE-94, CWE-74

Which versions are affected by CVE-2026-4963?

3 open source packages ship an affected version, including smolagents. It affects 1 product.

Products include Huggingface Smolagents.

How do I fix CVE-2026-4963?

No fix has been published for CVE-2026-4963 yet. Limit exposure of the affected software until one is available.

Upgrade, and never evaluate templates, expressions or code built from user input. More about Code injection.

Is CVE-2026-4963 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-4963 exists.

Other vulnerabilities in huggingface smolagents

• CVE-2025-5120 Sandbox Escape Vulnerability in huggingface/smolagents High 7.6
• CVE-2025-11844 XPath Injection in Hugging Face Smolagents search_item_ctrl_f Function Medium 5.4
• CVE-2026-2654 huggingface smolagents LocalPythonExecutor requests.post server-side request forgery Medium 5.3

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as GHSA-54fq-v6x8-244g, PYSEC-2026-3066.