CVE-2026-58166: OpenBMB ChatDev path traversal in file upload handler

CVE-2026-58166 · Severity: critical · CVSS 9.1 · Published 2026-06-30

OpenBMB ChatDev, a platform for AI-driven software development, contains a security flaw in its file upload system. An unauthenticated attacker can exploit this to write or delete any file on the server's filesystem. This could lead to a complete system takeover by overwriting critical configuration files or a total loss of data through arbitrary file deletion.

Vendors: OpenBMB.

Quick answers

Is CVE-2026-58166 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-58166 being exploited in the wild.
How severe is CVE-2026-58166?
Critical severity, with a CVSS score of 9.1, published 30 June 2026.
Which products and versions are affected?
OpenBMB ChatDev through 2.2.0.
Is there a fix for CVE-2026-58166?
A patch was published on 2026-06-29: Fix merged in commit 4fd4da6 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-58166 attacked?
It is attacked over the network, in a network appliance.
Am I affected by CVE-2026-58166?
Check whether you run OpenBMB ChatDev at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

A path traversal vulnerability exists in the `save_upload_file` function within `server/services/attachment_service.py`. The application fails to sanitize the client-provided multipart filename before joining it with a temporary directory path. An unauthenticated attacker can send a POST request to the `/api/uploads/{session_id}` endpoint with a filename containing traversal sequences (e.g., `../../`). This causes the application to write uploaded content to an arbitrary location and subsequently delete the same file during the `finally` cleanup block's `unlink()` operation. The vulnerability is exploitable without authentication as session IDs are minted freely by the workflow server. A fix is available in commit 4fd4da6.

Affected products

  • OpenBMB ChatDev through 2.2.0

Timeline

  • 2026-06-12: disclosed: Issue reported to vendor via GitHub
  • 2026-06-29: patched: Fix merged in commit 4fd4da6
  • 2026-06-30: advisory: CVE-2026-58166 published

References

This page as Markdown. Free to reuse under CC BY 4.0 with a link back.