CVE-2026-24773: Open eClass IDOR Vulnerability Exposed

CVE-2026-24773 Overview

CVE-2026-24773 is an Insecure Direct Object Reference (IDOR) vulnerability affecting the Open eClass platform (formerly known as GUnet eClass), a complete course management system used in educational environments. Prior to version 4.2, the platform fails to properly validate user authorization when accessing personal files, allowing unauthenticated remote attackers to access personal files belonging to other users by directly requesting predictable user identifiers.

Critical Impact

Unauthenticated attackers can remotely access sensitive personal files of any user on the platform by exploiting predictable user identifiers, potentially exposing confidential educational records, assignments, and personal documents.

Affected Products

• Open eClass platform versions prior to 4.2
• GUnet eClass (legacy name) versions prior to 4.2

Discovery Timeline

• 2026-02-03 - CVE CVE-2026-24773 published to NVD
• 2026-02-04 - Last updated in NVD database

Technical Details for CVE-2026-24773

Vulnerability Analysis

This vulnerability is classified under CWE-639 (Authorization Bypass Through User-Controlled Key), which occurs when an application uses user-supplied input to access objects directly without proper authorization verification. In the context of Open eClass, the platform implements a file access mechanism that relies on predictable user identifiers to retrieve personal files. The application fails to verify whether the requesting user has legitimate authorization to access the requested resource.

The network-accessible nature of this vulnerability means attackers can exploit it remotely without requiring any prior authentication to the system. The attack complexity is low, as exploitation requires only the ability to enumerate or predict user identifiers and craft appropriate HTTP requests to the vulnerable endpoint.

Root Cause

The root cause of CVE-2026-24773 lies in the application's failure to implement proper authorization checks when serving user files. The file access functionality accepts user identifiers directly in requests without validating that the authenticated session (or lack thereof) has permission to access the specified user's files. This represents a fundamental access control design flaw where the application trusts user-supplied input to determine which resources to serve.

The predictable nature of user identifiers compounds this issue, as attackers can easily enumerate valid user IDs through sequential testing or pattern analysis, enabling systematic data exfiltration across multiple user accounts.

Attack Vector

The attack vector exploits the network-accessible file retrieval functionality in Open eClass. An unauthenticated attacker can directly request files belonging to any user by manipulating user identifier parameters in HTTP requests. Since the application does not verify authorization, it returns the requested files regardless of whether the requester has legitimate access rights.

The exploitation process typically involves:

1. Identifying the vulnerable file access endpoint in the Open eClass installation
2. Enumerating or guessing valid user identifiers (often sequential integers or predictable patterns)
3. Crafting HTTP requests with target user identifiers to retrieve their personal files
4. Iterating through multiple user identifiers to access files across the entire user base

For detailed technical information about this vulnerability, refer to the GitHub Security Advisory.

Detection Methods for CVE-2026-24773

Indicators of Compromise

• Unusual patterns of file access requests with sequential or enumerated user identifiers
• High volume of file retrieval requests from single IP addresses targeting multiple user accounts
• Access logs showing unauthenticated requests to user file endpoints
• Anomalous traffic patterns to file download endpoints during off-hours

Detection Strategies

• Monitor web application logs for requests containing varying user identifiers from the same source
• Implement rate limiting and anomaly detection on file access endpoints
• Deploy web application firewall (WAF) rules to detect parameter enumeration attempts
• Configure alerting for bulk file access patterns that deviate from normal user behavior

Monitoring Recommendations

• Enable detailed access logging for all file retrieval endpoints in Open eClass
• Implement user behavior analytics to establish baseline access patterns and detect anomalies
• Monitor for sequential parameter enumeration in web server logs
• Set up alerts for access attempts to files belonging to multiple different users from single sessions

How to Mitigate CVE-2026-24773

Immediate Actions Required

• Upgrade Open eClass installations to version 4.2 or later immediately
• Audit access logs to identify potential past exploitation attempts
• Review and restrict network access to Open eClass installations where possible
• Notify users of potential data exposure if exploitation evidence is found

Patch Information

The Open eClass development team has addressed this vulnerability in version 4.2. Organizations running affected versions should upgrade to version 4.2 or later to remediate this IDOR vulnerability. The patch implements proper authorization checks to ensure users can only access their own files.

For detailed patch information and upgrade instructions, consult the GitHub Security Advisory.

Workarounds

• Implement network-level access controls to restrict access to the Open eClass installation to trusted IP ranges
• Deploy a web application firewall (WAF) with rules to detect and block parameter enumeration attempts
• Consider temporarily disabling the file sharing functionality until the patch can be applied
• Implement additional authentication requirements at the reverse proxy or load balancer level

# Example: Restrict access to Open eClass via firewall (iptables)
# Allow only trusted networks to access the application
iptables -A INPUT -p tcp --dport 443 -s 10.0.0.0/8 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP