The Kotaemon platform, up to version 0.12.0, contains a flaw that fails to verify conversation ownership when a user invokes select_conv, delete_conv, rename_conv, or set_public_conversation functions. This omission allows an attacker possessing a valid session to supply arbitrary conversation identifiers, thereby reading, deleting, or renaming conversations belonging to other users. The weakness is a type of authorization bypass (CWE‑639), exposing both confidential chat history and the ability to tamper with other users’ data.

The affected product is Kotaemon maintained by Cinnamon. All releases through 0.12.0 lack the proper ownership checks and are affected by this vulnerability.

The CVSS score of 9.1 indicates a high severity. The EPSS score is not available, and this issue is not listed in the CISA KEV catalog, implying no publicly known exploits at this time. Based on the description, the likely attack vector is through authenticated users who can craft requests directly to the control interface; an attacker could supply an arbitrary conversation ID and trigger the unauthorized action without additional privileges. Exploitation requires only the ability to reach the API or web interface and a valid user session, making it a significant risk for environments where user authentication is not tightly scoped or where session hijacking is possible.