ChromaDB Cross-Tenant IDOR via Collection Lookup UUID

Insecure Direct Object Reference (IDOR) in Collection Lookup Leading to Cross-Tenant Data Access Vulnerability Overview Any authenticated user possessing a valid Collection UUID can read, write, update, or delete data within collections belonging to any tenant, regardless of their own tenant affiliation. ChromaDB's collection lookup mechanism bypasses tenant and database filters when a UUID is provided. Affected Versions This vulnerability affects all versions of ChromaDB from 0.4.17 up to the latest release. CVSS Score 8.8 CWE Classification CWE-639: Authorization Bypass Through User-Controlled Key Details The vulnerability is caused by two code paths that collectively undermine tenant isolation: 1. The first is an SQL query that skips tenant filtering when a UUID is provided. 2. The second is the method, which passes only the UUID without tenant context. Code Example Timeline February 17, 2026: Initial disclosure to ChromaDB February 24, 2026: Follow-up attempt via other trychroma emails March 5, 2026: Attempted contact through IT-ISAC April 10, 2026: Final follow-up attempt via all previous channels and social media May 19, 2026: Public disclosure of the first vulnerability; no response received from the vendor Project URLs https://www.trychroma.com/ https://github.com/chroma-core/chroma/ Researchers Esteban Tonglet, Security Researcher, HiddenLayer

Goal Reached Thanks to every supporter — we hit 100%!

ChromaDB Cross-Tenant IDOR via Collection Lookup UUID