# CVE-2026-7846: chatchat-space Langchain-Chatchat OpenAI-Compatible File Upload API openai_routes.py files toctou

> Attackers can exploit a race condition in the file upload API to bypass security checks, requiring local network access and high complexity.

- **Severity:** Low 2.1 (`CVSS:4.0/AV:A/AC:H/AT:N/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 5 May 2026
- **Updated:** 5 May 2026
- **Also known as:** GHSA-x229-w2j4-h748, PYSEC-2026-2559

## What is CVE-2026-7846?

CVE-2026-7846 is a low-severity vulnerability in chatchat-space Langchain-Chatchat, published on 5 May 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

A vulnerability has been found in chatchat-space Langchain-Chatchat up to 0.3.1.3. Impacted is the function files of the file libs/chatchat-server/chatchat/server/api_server/openai_routes.py of the component OpenAI-Compatible File Upload API. Such manipulation of the argument file.filename leads to time-of-check time-of-use. Access to the local network is required for this attack to succeed. The attack requires a high level of complexity. The exploitability is considered difficult. The exploit has been disclosed to the public and may be used. The project was informed of the problem early through an issue report but has not responded yet.

Weakness: CWE-367 (Time-of-check Time-of-use (TOCTOU) Race Condition), CWE-362 (Concurrent Execution using Shared Resource with Improper Synchronization)

## Which versions are affected by CVE-2026-7846?

3 open source packages ship an affected version, including langchain-chatchat.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `langchain-chatchat` | PyPI | All versions to 0.3.1.3 | None |
| `langchain-chatchat` | PyPI | All versions to 0.3.1.3 | None |
| `langchain-chatchat` | PyPI | All versions to 0.3.1.3 | None |

## How do I fix CVE-2026-7846?

No fix has been published for CVE-2026-7846 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-7846 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-7846 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-7846 and fix it if it is affected.

What it is: CVE-2026-7846 is a low-severity vulnerability in chatchat-space Langchain-Chatchat, published on 5 May 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-7846 exists.

Affected packages and fixed versions:
- langchain-chatchat (PyPI): affected all versions up to 0.3.1.3; no fix listed
- langchain-chatchat (PyPI): affected all versions up to 0.3.1.3; no fix listed
- langchain-chatchat (PyPI): affected all versions up to 0.3.1.3; 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-2026-7846/ (Markdown: https://insights.sbomify.com/CVE-2026-7846/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-7846
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-7846
- OSV: https://osv.dev/vulnerability/CVE-2026-7846

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-7846/
Summaries are generated and may contain mistakes; the official description above is the record.