CVE-2026-45831: ChromaDB Authorization Bypass Allows Cross-Tenant Data Access

Technical summary

CVE-2026-45831 is an authorization context validation failure in ChromaDB's SimpleRBACAuthorizationProvider. The provider implements role-based access control (RBAC) by checking whether a principal holds a required permission, but the implementation lacks scope binding—it does not verify that the permission is scoped to the specific tenant, database, or collection being accessed. This allows a user with legitimate permissions in one context to perform the same action across other contexts, effectively bypassing multi-tenancy and collection-level isolation. The vulnerability is classified as CWE-863 (Incorrect Authorization).

Business impact

Organizations using ChromaDB as a vector database or AI application backend face severe data isolation risks. An authenticated user—whether internal or with delegated API access—can exfiltrate sensitive embeddings or documents from other tenants or projects, modify or delete critical data across organizational boundaries, or poison datasets for machine learning workflows. In multi-tenant SaaS deployments, this violates fundamental data separation guarantees. Financial services, healthcare, and research institutions storing confidential data in ChromaDB face regulatory and reputational harm.

Affected systems

ChromaDB (trychroma chromadb) versions 0.5.0 and later are affected. The vulnerability exists in the SimpleRBACAuthorizationProvider authorization provider specifically. Organizations running ChromaDB with RBAC enabled and multiple tenants, databases, or collections should assume they are at risk. Deployments using alternative authorization providers or single-tenant architectures may have reduced exposure, though verification against your configuration is necessary.

Exploitability

The vulnerability requires authentication (PR:L in the CVSS vector) but no user interaction. An authenticated attacker with any valid credential can immediately attempt cross-tenant or cross-collection access. No special tools or conditions are needed—standard API calls to ChromaDB are sufficient. The attack surface is high for any deployment exposing ChromaDB to multiple users or tenants. The low attack complexity and straightforward nature of authorization bypass exploits make this practically exploitable in most deployments.

Remediation

Upgrade ChromaDB to a patched version that properly validates authorization scope against the target tenant, database, and collection. Verify the exact patch version and release notes from the ChromaDB project; this advisory does not specify a fixed version. Immediately audit logs for cross-tenant or cross-collection access patterns that suggest exploitation. Isolate ChromaDB instances or enforce network-level access controls if patching is delayed. For multi-tenant environments, consider temporary application-level authorization checks until patches are deployed.

Patch guidance

Check the ChromaDB project repository and release notes for versions after 0.5.0 that explicitly address this authorization bypass. Apply the patch as soon as it is available and verified. Test thoroughly in a staging environment, particularly with multi-tenant and multi-collection scenarios, before production deployment. Verify that authorization checks now validate tenant, database, and collection scope in addition to permission presence.

Detection guidance

Monitor ChromaDB audit and access logs for anomalous cross-tenant or cross-collection queries from authenticated users. Look for API calls that access collections or databases outside the user's expected scope. Implement alerting on permission-granted operations followed by access to unexpected tenants or databases. Review authentication logs for newly created service accounts or API keys that precede unusual access patterns. Network-level detection of ChromaDB queries to unexpected internal databases can supplement application-level monitoring.

Why prioritize this

This is a HIGH-severity flaw (CVSS 8.8) affecting a foundational security control—authorization—with immediate practical exploitability requiring only authentication. The complete compromise of confidentiality, integrity, and availability in affected contexts, combined with multi-tenancy being a core ChromaDB use case, warrants urgent patching. Organizations running multi-tenant or multi-collection ChromaDB deployments should prioritize this above most other patches.

Risk score, explained

The CVSS 8.8 score reflects a network-accessible authorization bypass with low attack complexity. Authentication is required, limiting the threat to authorized users; however, the scope is unchanged (single system, no privilege escalation), and all three security impacts (confidentiality, integrity, availability) are fully compromised. The high score appropriately captures the severity of authorization bypass in a multi-tenant architecture where isolation is a core security boundary.

Frequently asked questions