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

> Remote attackers can execute arbitrary code via incomplete fixes in the local Python executor of the smolagents library.

- **Severity:** Medium 5.3 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 27 Mar 2026
- **Updated:** 31 Mar 2026
- **Also known as:** GHSA-54fq-v6x8-244g, PYSEC-2026-3066

## 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 (Improper Control of Generation of Code), CWE-74 (Improper Neutralization of Special Elements in Output Used by a Downstream Component)

## Which versions are affected by CVE-2026-4963?

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


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `smolagents` | PyPI | All versions to 1.25.0.dev0 | None |
| `smolagents` | PyPI | All versions to 1.25.0.dev0 | None |
| `smolagents` | PyPI | All versions to 1.25.0.dev0 | None |

Products: 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.

## 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](https://insights.sbomify.com/CVE-2025-5120/): Sandbox Escape Vulnerability in huggingface/smolagents (high 7.6)
- [CVE-2025-11844](https://insights.sbomify.com/CVE-2025-11844/): XPath Injection in Hugging Face Smolagents search_item_ctrl_f Function (medium 5.4)
- [CVE-2026-2654](https://insights.sbomify.com/CVE-2026-2654/): huggingface smolagents LocalPythonExecutor requests.post server-side request forgery (medium 5.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-4963 and fix it if it is affected.

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

Affected packages and fixed versions:
- smolagents (PyPI): affected all versions up to 1.25.0.dev0; no fix listed
- smolagents (PyPI): affected all versions up to 1.25.0.dev0; no fix listed
- smolagents (PyPI): affected all versions up to 1.25.0.dev0; no fix listed

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-4963/ (Markdown: https://insights.sbomify.com/CVE-2026-4963/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-4963
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-4963
- OSV: https://osv.dev/vulnerability/CVE-2026-4963

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-4963/
Summaries are generated and may contain mistakes; the official description above is the record.