Authorization Bypass in Kotaemon Chat Interface

Executive Summary

CVE-2026-86867 is an authorization vulnerability in Cinnamon's Kotaemon (versions up to v0.12.0) that allows any authenticated user to access, modify, or delete conversations belonging to other users. The system fails to verify conversation ownership when loading conversations, enabling unauthorized actions such as reading chat transcripts, deleting conversations, renaming conversations, or overwriting chat suggestions.

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Detection Guidance

Check for unauthorized access to chat transcripts or conversation modifications by reviewing logs for actions performed by users on conversations they do not own. Look for repeated attempts to access conversations using different user IDs. Monitor for unexpected deletions or renames of conversations.

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Impact Analysis

This vulnerability allows attackers with a valid account to read sensitive data like chat transcripts, retrieval history containing private document excerpts, AI-generated plots, and chat suggestions. They can also permanently delete, rename, or overwrite another user's conversations, leading to data loss, misinformation, or unauthorized access to proprietary information.

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Compliance Impact

This vulnerability likely violates GDPR and HIPAA by exposing sensitive personal or health data through unauthorized access to chat transcripts and retrieval history. It compromises data confidentiality and integrity, potentially leading to regulatory penalties for non-compliance with privacy and security requirements.

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Mitigation Strategies

Disable multi-user functionality if possible. Restrict access to conversation UUIDs by reviewing and updating privacy settings. Implement network-level monitoring to detect unusual access patterns. Monitor for unauthorized deletions or modifications of conversations.

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