CVE-2026-82281: Kotaemon Information Disclosure Vulnerability

CVE-2026-82281 Overview

CVE-2026-82281 is an authorization bypass vulnerability in Kotaemon versions through 0.12.0. The application fails to validate conversation ownership in the select_conv, delete_conv, rename_conv, and on_set_public_conversation functions within control.py. Authenticated attackers can supply arbitrary conversation identifiers to read other users' chat histories, delete their conversations, or rename them without any authorization enforcement. The flaw is categorized as an Insecure Direct Object Reference under CWE-639. Kotaemon is an open-source retrieval-augmented generation (RAG) chat application widely used for document question-answering workflows.

Critical Impact
Any authenticated Kotaemon user can access, modify, or destroy conversation data belonging to other users, resulting in confidentiality and integrity loss across all tenants of a shared deployment.

Affected Products

Kotaemon versions through 0.12.0
Deployments using the libs/ktem/ktem/pages/chat/control.py conversation control module
Multi-user Kotaemon instances exposing the chat UI over the network

Discovery Timeline

2026-08-28 - CVE-2026-82281 published to NVD
2026-08-31 - Last updated in NVD database

Technical Details for CVE-2026-82281

Vulnerability Analysis

Kotaemon exposes conversation management endpoints that accept a conversation identifier from the client. The affected handlers in control.py retrieve, mutate, or delete the referenced conversation record without verifying that the requesting user owns it. Because conversation IDs are predictable database references, an attacker enumerating or guessing IDs gains full CRUD access to other tenants' chat data. The impact scope covers stored prompts, model responses, uploaded document context, and conversation metadata. This is a textbook Insecure Direct Object Reference pattern where authentication succeeds but authorization is never enforced.

Root Cause

The root cause is the absence of an ownership check between the authenticated session user and the user_id associated with the conversation record. The select_conv, delete_conv, rename_conv, and on_set_public_conversation functions query or modify conversation rows using only the supplied identifier. No WHERE user_id = current_user predicate or equivalent server-side authorization guard is applied before executing the operation.

Attack Vector

Exploitation requires network access to the Kotaemon web interface and a valid authenticated session. The attacker submits a crafted request to a vulnerable handler with a target conversation ID belonging to another user. The server returns the victim's chat history for select_conv, permanently removes the conversation for delete_conv, changes its title for rename_conv, or toggles its visibility flag for on_set_public_conversation. Refer to the VulnCheck Advisory on Kotaemon and the GitHub Issue #846 for technical details. No verified proof-of-concept code is published, so exploit mechanics are described in prose rather than reproduced here.

Detection Methods for CVE-2026-82281

Indicators of Compromise

Application logs showing conversation reads, renames, or deletions where the requesting session user does not match the stored user_id on the target conversation.
Sudden spikes in select_conv or delete_conv calls from a single account referencing sequential or randomized conversation IDs.
Unexpected on_set_public_conversation events flipping private conversations to public.
User reports of missing, renamed, or unexpectedly public conversations without corresponding owner action.

Detection Strategies

Instrument the four affected handlers in control.py to log the tuple (session user_id, conversation user_id, operation) and alert on any mismatch.
Add SQL or ORM query auditing to flag conversation-table access patterns that iterate across multiple owner IDs from one session.
Correlate authentication logs with conversation-modification events to identify low-reputation or newly created accounts touching high volumes of records.

Monitoring Recommendations

Retain conversation-CRUD audit logs for at least 90 days to support incident review.
Configure alerts on deletion volume anomalies per user account.
Monitor the Kotaemon GitHub repository for the fix commit and downstream package releases.

How to Mitigate CVE-2026-82281

Immediate Actions Required

Restrict Kotaemon access to trusted users only until a patched release is deployed, using network ACLs, VPN, or reverse-proxy authentication.
Disable public registration on multi-tenant instances to reduce the pool of authenticated attackers.
Audit existing conversation records for unexpected owners, public flags, or missing entries and restore from backup where necessary.
Rotate any secrets or sensitive data that may have been exposed through cross-user conversation reads.

Patch Information

At the time of publication, no fixed release beyond Kotaemon 0.12.0 is referenced in the advisory. Track GitHub Issue #846 and the upstream Kotaemon repository for the remediation commit. The required fix is to add an ownership predicate in select_conv, delete_conv, rename_conv, and on_set_public_conversation inside control.py so that each operation requires the session user_id to match the conversation's stored user_id.

Workarounds

Deploy Kotaemon as a single-user instance per operating-system user or per container to eliminate the cross-tenant threat model.
Place the application behind an authenticating reverse proxy that scopes each user to an isolated backend instance.
Apply a local patch that wraps each vulnerable handler with an ownership check before the database call, pending an official release.

bash

# Configuration example: restrict Kotaemon to trusted network only
# Example nginx snippet enforcing IP allowlist in front of Kotaemon
location / {
    allow 10.0.0.0/8;
    deny  all;
    proxy_pass http://127.0.0.1:7860;
}