CVE-2026-11369: Comment API Auth Bypass Vulnerability

CVE-2026-11369 Overview

CVE-2026-11369 is an Insecure Direct Object Reference (IDOR) vulnerability affecting the Comment API in Linqi. The flaw exists in the GET /api/Comment and POST /api/Comment endpoints, which fail to verify whether the requesting user has authorization to access the object referenced by relatedObjectId. Any authenticated user can read and write comments on any process across all business units by supplying an arbitrary object GUID. The weakness is classified under [CWE-639] (Authorization Bypass Through User-Controlled Key).

Critical Impact
Authenticated attackers can read and modify comments on arbitrary process objects across tenant boundaries, exposing confidential business data and enabling cross-business-unit data tampering.

Affected Products

Linqi process automation platform (Comment API)
Refer to the Linqi Security Advisory on IDOR for affected versions

Discovery Timeline

2026-06-05 - CVE-2026-11369 published to NVD
2026-06-05 - Last updated in NVD database

Technical Details for CVE-2026-11369

Vulnerability Analysis

The Comment API in Linqi exposes two endpoints, GET /api/Comment and POST /api/Comment, that operate on objects identified by a relatedObjectId GUID. The API authenticates the caller but does not validate that the authenticated user has authorization to access the referenced object. An attacker holding any valid account can submit requests referencing arbitrary GUIDs to read existing comments or inject new comments on processes owned by other users or business units. The flaw breaches tenant and business-unit isolation, exposing sensitive comment content and enabling unauthorized writes that may influence downstream workflows.

Root Cause

The root cause is a missing server-side authorization check between authentication and object retrieval. The endpoint trusts the client-supplied relatedObjectId value without enforcing an access control rule that ties the requesting user identity to the target object's owner or business unit. This matches the [CWE-639] pattern of authorization decisions based on user-controlled keys.

Attack Vector

Exploitation requires only network access and a low-privilege authenticated session. An attacker enumerates or guesses valid object GUIDs, then issues GET /api/Comment?relatedObjectId=<guid> requests to harvest comment data or POST /api/Comment requests to inject content. No user interaction or elevated privileges are required, and the action can be repeated programmatically to traverse multiple business units.

No public proof-of-concept code is available. See the Linqi Security Advisory on IDOR for vendor technical detail.

Detection Methods for CVE-2026-11369

Indicators of Compromise

Unusual volumes of GET /api/Comment requests from a single authenticated session referencing many distinct relatedObjectId values
POST /api/Comment requests originating from accounts that have no prior interaction history with the referenced process objects
Sequential or enumerative GUID patterns appearing in Comment API access logs
Cross-business-unit access patterns where a user reads or writes comments outside their assigned tenant scope

Detection Strategies

Correlate authenticated user identity against the owning business unit of each relatedObjectId and alert on mismatches
Baseline normal per-user Comment API request rates and flag statistical anomalies
Inspect application audit logs for comment writes by accounts that do not have a process assignment relationship to the target object

Monitoring Recommendations

Enable verbose request logging on /api/Comment endpoints, capturing user ID, relatedObjectId, and HTTP method
Forward Linqi application and access logs to a centralized SIEM for cross-user correlation and retention
Configure alerting on first-time access patterns where a user touches process objects from previously unseen business units

How to Mitigate CVE-2026-11369

Immediate Actions Required

Apply the vendor patch referenced in the Linqi Security Advisory on IDOR as soon as it is available for your deployment
Audit recent Comment API activity for cross-business-unit access and review affected processes for unauthorized comments
Restrict access to the Linqi application to trusted networks and authenticated identities until patched

Patch Information

Consult the official Linqi Security Advisory on IDOR for fixed version information and upgrade guidance. Apply the vendor-supplied update across all Linqi instances and verify post-upgrade that authorization checks are enforced on both GET and POST Comment endpoints.

Workarounds

Where patching is not immediately possible, place the Comment API behind an API gateway or reverse proxy that enforces user-to-object ownership checks before forwarding requests
Reduce account provisioning to least privilege and disable inactive accounts to shrink the pool of authenticated identities that could exploit the flaw
Monitor and rate-limit Comment API requests per user to slow enumeration attempts until a patch is applied

bash

# Example reverse-proxy rate limit and logging (NGINX)
limit_req_zone $http_authorization zone=comment_api:10m rate=10r/m;

location /api/Comment {
    limit_req zone=comment_api burst=5 nodelay;
    access_log /var/log/nginx/comment_api.log combined;
    proxy_pass http://linqi_backend;
}