CVE-2026-63235 Overview
CVE-2026-63235 is an improper access control vulnerability [CWE-284] in Koollab LMS. The flaw resides in the login kickout endpoint, which fails to authenticate the caller before terminating an active user session. An unauthenticated attacker can supply any registered user's email address to the endpoint and forcibly log that user out. Repeatedly invoking the endpoint produces a targeted denial-of-service condition against individual accounts. The issue is network-reachable and requires no privileges or user interaction, though exploitation complexity is rated high.
Critical Impact
Unauthenticated attackers can forcibly terminate any user's active session by submitting the target's email address, denying access to Koollab LMS on demand.
Affected Products
- Koollab LMS (specific version range not disclosed in the advisory)
- Deployments exposing the login kickout endpoint to untrusted networks
- Learner and administrator accounts that authenticate through the affected endpoint
Discovery Timeline
- 2026-07-29 - CVE-2026-63235 published to NVD
- 2026-07-30 - Last updated in NVD database
Technical Details for CVE-2026-63235
Vulnerability Analysis
The vulnerability exists in the login kickout endpoint of Koollab LMS. This endpoint is designed to terminate an authenticated user's active session, typically as part of administrative session-management workflows. In the affected build, the endpoint accepts an email address parameter and executes the session termination logic without verifying the identity or authorization of the requester.
Because the endpoint enforces no authentication or authorization checks, any network-adjacent actor who can reach the LMS can invoke the kickout function against arbitrary accounts. The impact is limited to availability. Confidentiality and integrity are not affected, since no session data is returned to the attacker and no state beyond the target session is modified.
Sustained exploitation against high-value accounts, such as instructors during examinations or administrators during incident response, can meaningfully disrupt learning operations. The advisory published by the CSA Security Alert AL-2026-094 provides additional context.
Root Cause
The root cause is a missing access control check on the login kickout handler. The application trusts the supplied email parameter as sufficient input to authorize the destructive action. This is a classic instance of [CWE-284] Improper Access Control, where a security-sensitive operation is exposed without a corresponding authorization layer.
Attack Vector
An attacker sends a crafted HTTP request to the kickout endpoint with the victim's email address in the request body or query string. The server invalidates the victim's session token and forces the victim to re-authenticate. Repeated requests, potentially scripted, keep the victim in a login loop. Attacker prerequisites are limited to network reachability and knowledge or enumeration of a valid user email address.
No verified proof-of-concept code is publicly available. See the CSA Security Alert AL-2026-094 for vendor-coordinated details.
Detection Methods for CVE-2026-63235
Indicators of Compromise
- Unauthenticated HTTP requests to the Koollab LMS login kickout endpoint originating from external or untrusted IP ranges.
- Repeated session invalidation events for the same user account within short time windows.
- User complaints of unexpected logouts or persistent login prompts without account lockout events.
Detection Strategies
- Alert on requests to the kickout endpoint that lack a valid administrator session cookie or bearer token.
- Correlate session-termination events with the source IP that triggered them and flag mismatches between requester identity and target account.
- Baseline normal kickout call volume and alert on statistically significant spikes per account or per source address.
Monitoring Recommendations
- Enable verbose access logging on the LMS reverse proxy or web application firewall for all authentication-related endpoints.
- Forward LMS application and access logs to a centralized analytics platform for retention and correlation.
- Track failed login rates and forced logout counts per user as leading indicators of targeted denial-of-service activity.
How to Mitigate CVE-2026-63235
Immediate Actions Required
- Restrict network access to the Koollab LMS kickout endpoint using firewall or reverse-proxy allowlists until a patch is applied.
- Contact Koollab support to confirm patch availability and obtain fixed builds for the affected deployment.
- Rotate or invalidate any exposed administrative credentials that could compound the impact of forced logouts.
Patch Information
No fixed version is enumerated in the NVD entry at time of publication. Administrators should consult the vendor and the CSA Security Alert AL-2026-094 for remediation guidance and updated builds.
Workarounds
- Place the kickout endpoint behind an authenticated administrative path segment enforced at the reverse proxy.
- Apply rate limiting on the endpoint by source IP and by target account to blunt sustained abuse.
- Require a valid authenticated session cookie at the web application firewall before requests reach the LMS application layer.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
