# CVE-2026-81096: ToolUniverse through 1.2.6 Unauthenticated Remote Code Execution via python_code_executor Sandbox Escape


- **Severity:** Critical 9.3 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Fix available:** No
- **Published:** 27 Aug 2026
- **Updated:** 29 Aug 2026
- **Also known as:** GHSA-pxwq-22vf-87fm, GHSA-rg68-wg77-c3wm

## What is CVE-2026-81096?

CVE-2026-81096 is a critical vulnerability in mims-harvard ToolUniverse, published on 27 Aug 2026. 

### Official description

ToolUniverse ran caller-supplied Python inside a sandbox that could be escaped, on a server that required no authentication. The executor behind the python_code_executor tool, in python_executor_tool.py, inspected the submitted source for a denied list of attribute names and calls but left the attribute-lookup builtins available and did not stop a dunder attribute reached through a string lookup or through a module already permitted, so a caller could walk from a literal's class to its base and enumerate subclasses to obtain a reference to the process and subprocess modules. A per-call argument also let the caller widen the import allow-list before the inspection ran. The HTTP and MCP servers in http_api_server.py and smcp_server.py bound to every interface with debugging enabled and no authentication, so any caller able to reach the port executed code as the server process. Version 1.3.0 adds bearer-token authentication, defaults the bind address to loopback, and hardens the attribute checks.

Weakness: CWE-94 (Improper Control of Generation of Code)

## Which versions are affected by CVE-2026-81096?


## How do I fix CVE-2026-81096?

No fix has been published for CVE-2026-81096 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-81096 being exploited?

There is no known exploitation of CVE-2026-81096 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-81096 and fix it if it is affected.

What it is: CVE-2026-81096 is a critical vulnerability in mims-harvard ToolUniverse, published on 27 Aug 2026. 
Exploitation: There is no known exploitation of CVE-2026-81096 in the wild and no public exploit code.

Affected product: mims-harvard ToolUniverse. No package-level version data is available, so check the vendor advisory linked from the reference page.

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-2026-81096/ (Markdown: https://insights.sbomify.com/CVE-2026-81096/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-81096
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-81096
- OSV: https://osv.dev/vulnerability/CVE-2026-81096

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-81096/
Summaries are generated and may contain mistakes; the official description above is the record.