CVE-2025-67259: ClassroomIO Access Control Vulnerability

CVE-2025-67259 Overview

A Broken Access Control vulnerability exists in ClassroomIO v0.1.13 that allows an authenticated low-privileged "student" user to access unauthorized course-level information by modifying intercepted API requests. By changing a captured POST request to a GET request against the /rest/v1/course PostgREST endpoint, attackers can disclose sensitive information including other students' details, tutor/admin profiles, and internal course metadata.

Critical Impact
Authenticated students can bypass access controls to expose sensitive user data and internal course information through simple HTTP method manipulation.

Affected Products

ClassroomIO v0.1.13

Discovery Timeline

2026-04-24 - CVE CVE-2025-67259 published to NVD
2026-04-24 - Last updated in NVD database

Technical Details for CVE-2025-67259

Vulnerability Analysis

This vulnerability represents a classic Broken Access Control flaw (CWE-284) where the application fails to properly enforce authorization checks based on HTTP request methods. The PostgREST endpoint at /rest/v1/course accepts both POST and GET requests but does not consistently validate user permissions across different HTTP methods.

When a student user interacts with the course API through normal application flow, POST requests are used with appropriate access restrictions. However, the underlying API endpoint accepts GET requests without equivalent authorization validation, allowing authenticated students to retrieve data they should not have access to.

Root Cause

The root cause lies in inconsistent access control implementation across HTTP methods on the PostgREST /rest/v1/course endpoint. The application enforces role-based permissions for POST operations but fails to apply the same restrictions to GET requests on the same endpoint. This differential treatment of HTTP methods creates an authorization bypass vector that authenticated low-privileged users can exploit.

Attack Vector

The attack is network-based and requires low privileges (an authenticated student account). An attacker intercepts a legitimate POST request to the /rest/v1/course endpoint using a web proxy tool, then modifies the HTTP method from POST to GET before forwarding the request to the server.

The vulnerability manifests when the server processes the modified GET request without properly validating whether the authenticated user has permission to read the requested course data. This results in the server returning sensitive information including:

Other enrolled students' personal details
Tutor and administrator profile information
Internal course metadata and configuration data

For detailed technical analysis, see the GitHub Issue Discussion and the supplementary documentation.

Detection Methods for CVE-2025-67259

Indicators of Compromise

Unusual GET requests to /rest/v1/course endpoints from student accounts that typically use POST
High volume of API requests from a single student user querying multiple course endpoints
Access log entries showing HTTP method switching patterns (POST followed by GET to same resource)

Detection Strategies

Implement logging and alerting for HTTP method changes on the same endpoint from the same session
Monitor for unauthorized data access patterns where students query course information outside their enrolled courses
Deploy Web Application Firewall (WAF) rules to detect and block suspicious method manipulation attempts

Monitoring Recommendations

Enable detailed API access logging on PostgREST endpoints to track all request methods and user contexts
Create alerts for student accounts accessing administrative or instructor-level course metadata
Review access logs periodically for patterns of enumeration or bulk data retrieval from course endpoints

How to Mitigate CVE-2025-67259

Immediate Actions Required

Upgrade ClassroomIO beyond version v0.1.13 when a patched version becomes available
Implement server-side access control checks that validate user permissions regardless of HTTP method
Review and restrict PostgREST endpoint configurations to enforce consistent role-based access control

Patch Information

No official patch information is currently available. Monitor the ClassroomIO GitHub repository for security updates and patch releases.

Workarounds

Configure PostgREST row-level security policies to enforce proper access controls at the database level
Implement API gateway rules to restrict GET requests on sensitive endpoints to authorized roles only
Add middleware validation to verify user permissions before processing any course data requests regardless of HTTP method

bash

# Example PostgREST RLS policy configuration concept
# Apply row-level security to ensure students can only access their enrolled course data
# ALTER TABLE courses ENABLE ROW LEVEL SECURITY;
# CREATE POLICY student_course_access ON courses
#   FOR SELECT
#   USING (auth.uid() IN (SELECT student_id FROM enrollments WHERE course_id = courses.id));