CVE-2026-63241: Koollab LMS Information Disclosure Flaw

CVE-2026-63241 Overview

CVE-2026-63241 is an Insecure Direct Object Reference (IDOR) vulnerability in Koollab LMS. An authenticated user can query the course completion progress of any other user without authorization. The flaw discloses private learning progress information belonging to other platform users.

The issue is tracked under CWE-639: Authorization Bypass Through User-Controlled Key. Exploitation requires network access, low privileges, and no user interaction, but has high attack complexity. The vulnerability affects confidentiality only; integrity and availability are not impacted.

Critical Impact
Any authenticated Koollab LMS user can enumerate and read the course completion progress of arbitrary other users, exposing private learning records.

Affected Products

Koollab LMS (specific affected versions not enumerated in the advisory)

Discovery Timeline

2026-07-29 - CVE-2026-63241 published to NVD
2026-07-30 - Last updated in NVD database
Referenced advisory - CSA Security Advisory AL-2026-094

Technical Details for CVE-2026-63241

Vulnerability Analysis

The vulnerability is an Insecure Direct Object Reference in Koollab LMS's course progress functionality. The application accepts a user identifier as part of a request to retrieve course completion progress. The backend returns the requested data based on the supplied identifier without verifying whether the requesting session owns that identifier or has been granted access to the target user's progress record.

An authenticated attacker can iterate through user identifiers and retrieve progress data for arbitrary accounts. Because access is scoped only by session authentication and not by object-level authorization, the attacker's own privileges do not constrain which records can be read.

The exposure is limited to learning progress information. Modification of records, session takeover, and service disruption are not part of the impact scope described in the advisory.

Root Cause

The root cause is missing object-level authorization on the course-progress query endpoint. The application trusts the client-supplied user identifier and does not enforce a check that the requester is the owner of the requested progress data or holds an administrator role. This maps directly to [CWE-639].

Attack Vector

Exploitation requires an authenticated session on the Koollab LMS instance. The attacker substitutes another user's identifier in a legitimate progress-query request. The server responds with the target user's course completion progress. No elevated privileges, tokens, or user interaction from the victim are required.

No verified proof-of-concept code has been published. See the CSA Security Advisory AL-2026-094 for vendor-supplied technical details.

Detection Methods for CVE-2026-63241

Indicators of Compromise

Repeated requests from a single authenticated session to progress endpoints with sequentially varying user identifiers.
Application access logs showing one user session retrieving progress records associated with many distinct user IDs in a short window.
Unusual volume of successful 200 responses to progress-query APIs where the session user does not match the queried user parameter.

Detection Strategies

Instrument the LMS to log both the authenticated session's user ID and the user ID supplied in progress-query parameters, then alert on mismatches.
Deploy web application firewall rules that flag high-cardinality enumeration of numeric or UUID user identifiers on progress endpoints.
Correlate authentication events with API access patterns to identify accounts performing broad reads of peer data.

Monitoring Recommendations

Baseline normal per-user query rates against progress endpoints and alert on statistical outliers.
Forward LMS application logs to a centralized analytics platform for retention and anomaly analysis.
Review privileged and service account activity for unexpected progress-endpoint queries.

How to Mitigate CVE-2026-63241

Immediate Actions Required

Apply the vendor patch or update referenced in CSA Security Advisory AL-2026-094 as soon as it is available.
Audit access logs for prior enumeration of progress records by non-administrative accounts.
Restrict LMS access to trusted networks or VPN where feasible to reduce the pool of authenticated actors.

Patch Information

Refer to the CSA Security Advisory AL-2026-094 for vendor remediation guidance. No specific fixed version was published in the NVD record at the time of writing.

Workarounds

Enforce server-side authorization checks that compare the session user ID to the requested resource owner on every progress-query response.
Replace predictable sequential identifiers with unguessable UUIDs to raise the cost of enumeration, understanding this is defense-in-depth, not a fix.
Apply rate limiting on progress-query endpoints per authenticated session to slow bulk data extraction.
Temporarily disable non-essential progress-reporting features for lower-privileged roles until the patch is applied.

bash

# Example: nginx rate limit on progress-query endpoint (defense-in-depth)
limit_req_zone $binary_remote_addr zone=progress:10m rate=10r/m;

location /api/courses/progress {
    limit_req zone=progress burst=5 nodelay;
    proxy_pass http://koollab_backend;
}