CVE-2025-0740: Thesamur Embedai Access Control Vulnerability

CVE-2025-0740 Overview

CVE-2025-0740 is an Improper Access Control vulnerability [CWE-284] affecting Thesamur EmbedAI version 2.1 and earlier. The flaw resides in the /embedai/chats/load_messages endpoint, which fails to verify that the requesting user owns the chat referenced by the chat_id parameter. An authenticated attacker can enumerate or guess CHAT_ID values to retrieve chat messages belonging to other users. The vulnerability exposes conversation contents without requiring elevated privileges or user interaction on the victim side.

Critical Impact
Authenticated attackers can read arbitrary users' chat histories by tampering with the chat_id query parameter, resulting in confidentiality loss across all EmbedAI tenants.

Affected Products

Thesamur EmbedAI 2.1
Thesamur EmbedAI versions prior to 2.1
Deployments exposing /embedai/chats/load_messages to authenticated users

Discovery Timeline

2025-01-30 - CVE-2025-0740 published to the National Vulnerability Database (NVD)
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-0740

Vulnerability Analysis

EmbedAI exposes an endpoint that loads chat messages using a client-supplied identifier: /embedai/chats/load_messages?chat_id=<CHAT_ID>. The endpoint authenticates the caller but does not enforce an authorization check tying the session identity to the requested chat_id. This pattern is a classic Insecure Direct Object Reference (IDOR) issue tracked under [CWE-284: Improper Access Control].

An attacker who holds any valid EmbedAI account can iterate chat_id values and receive full message contents from other users' conversations. Because EmbedAI is commonly used to embed chat assistants trained on private data, the returned messages may include proprietary content, credentials shared in chat, or personally identifiable information (PII).

The attack requires only network access to the application and a low-privileged authenticated session. No memory corruption, injection, or user interaction is involved.

Root Cause

The root cause is a missing ownership check on the chat_id parameter. The server-side handler retrieves messages from the datastore using the supplied identifier without validating that the authenticated principal is the owner or an authorized participant of that chat session.

Attack Vector

Exploitation is trivial. An authenticated attacker sends HTTP requests to the load_messages endpoint while iterating the chat_id query parameter. Identifiers may be sequential integers or predictable tokens, making enumeration straightforward.

The vulnerability manifests entirely in the authorization logic of the message-loading handler. No verified proof-of-concept code has been published; see the INCIBE CERT Notice on Vulnerabilities for the coordinated advisory.

Detection Methods for CVE-2025-0740

Indicators of Compromise

Repeated authenticated GET requests to /embedai/chats/load_messages with sequentially varying chat_id values from a single session or source IP.
HTTP 200 responses returning message bodies for chat_id values not previously associated with the requesting account.
Unusually high request volume against the load_messages endpoint outside typical user session patterns.

Detection Strategies

Correlate the authenticated user identifier with the owner of each requested chat_id in application logs, and alert on mismatches.
Deploy a Web Application Firewall (WAF) rule that flags rapid enumeration of the chat_id parameter from one session.
Baseline normal chat access patterns per user and alert on statistical outliers in accessed chat_id cardinality.

Monitoring Recommendations

Enable verbose request logging on the EmbedAI application tier and forward logs to a centralized analytics platform for retrospective hunting.
Monitor authentication events and correlate suspicious sessions with downstream load_messages activity.
Review data-loss-prevention (DLP) telemetry for outbound transfer of chat transcripts following suspicious enumeration activity.

How to Mitigate CVE-2025-0740

Immediate Actions Required

Upgrade EmbedAI to a version above 2.1 once a fixed release is published by Thesamur.
Restrict access to the EmbedAI application to trusted networks or authenticated VPN users while a patch is unavailable.
Rotate any credentials, API keys, or secrets that may have been shared through EmbedAI chats.
Audit application logs for prior exploitation attempts against /embedai/chats/load_messages.

Patch Information

No vendor patch URL is listed in the NVD entry for CVE-2025-0740 at the time of publication. Administrators should track vendor announcements and the INCIBE CERT Notice on Vulnerabilities for release information.

Workarounds

Place EmbedAI behind a reverse proxy that enforces per-user authorization on the chat_id parameter before proxying requests.
Implement a WAF rule that rate-limits requests to /embedai/chats/load_messages per authenticated session.
Replace predictable numeric chat_id values with unguessable Universally Unique Identifiers (UUIDs) at the storage layer to raise the exploitation barrier.
Temporarily disable the chat history loading feature if it is not business-critical.

bash

# Example NGINX rate-limit and access control snippet for the vulnerable endpoint
limit_req_zone $binary_remote_addr zone=embedai_msgs:10m rate=10r/m;

location /embedai/chats/load_messages {
    limit_req zone=embedai_msgs burst=5 nodelay;
    allow 10.0.0.0/8;
    deny all;
    proxy_pass http://embedai_backend;
}