CVE-2026-28354: Oxygenz Clipbucket Auth Bypass Flaw

CVE-2026-28354 Overview

CVE-2026-28354 is an authorization bypass vulnerability affecting ClipBucket v5, an open source video sharing platform. The vulnerability allows authenticated users to manipulate collection items belonging to other users due to missing and broken authorization checks in the collection management functionality.

Critical Impact

Attackers with low-privileged accounts can insert and remove items from collections they do not own, compromising data integrity across the platform.

Affected Products

• Oxygenz ClipBucket versions prior to 5.5.3 #59
• ClipBucket v5 installations with collection management features enabled

Discovery Timeline

• 2026-02-27 - CVE-2026-28354 published to NVD
• 2026-03-03 - Last updated in NVD database

Technical Details for CVE-2026-28354

Vulnerability Analysis

This vulnerability is classified as CWE-639 (Authorization Bypass Through User-Controlled Key), a type of Insecure Direct Object Reference (IDOR) flaw. The collection item operations in ClipBucket v5 fail to properly verify that the requesting user has ownership or appropriate permissions over the target collection before allowing modifications.

Two distinct endpoints are affected by this authorization weakness. The add item functionality at /actions/add_to_collection.php lacks any authorization checks, allowing any authenticated user to add items to arbitrary collections. The delete item functionality at /manage_collections.php?mode=manage_items... contains a broken ownership check in the removeItemFromCollection() function that fails to properly validate collection ownership before processing deletion requests.

Root Cause

The root cause of this vulnerability stems from inadequate access control implementation in the collection management module. The add_to_collection.php script processes requests without verifying the relationship between the authenticated user and the target collection. Similarly, the removeItemFromCollection() function contains flawed logic that does not properly enforce ownership verification, allowing the authorization check to be bypassed.

Attack Vector

An attacker with a valid low-privileged user account can exploit this vulnerability over the network without any user interaction. The attack involves sending crafted HTTP requests to the vulnerable endpoints with collection identifiers belonging to other users.

The exploitation requires:

1. A valid authenticated session on the ClipBucket platform
2. Knowledge of target collection identifiers (which may be enumerable or disclosed through the application)
3. Crafted requests to either add items to or remove items from collections owned by other users

Since the vulnerability exists in the web application layer and requires only standard HTTP requests, exploitation is straightforward for attackers with basic web application testing skills.

Detection Methods for CVE-2026-28354

Indicators of Compromise

• Unexpected modifications to user collections without corresponding user activity
• Log entries showing collection operations from IP addresses not associated with collection owners
• Multiple collection modification requests targeting different user accounts from a single session
• Anomalous patterns in collection item additions or deletions across multiple users

Detection Strategies

• Monitor web server access logs for requests to /actions/add_to_collection.php and /manage_collections.php endpoints with unusual patterns
• Implement application-level logging to track collection ownership versus requesting user identity
• Deploy web application firewalls (WAF) with rules to detect IDOR exploitation attempts
• Audit database logs for collection modification queries that don't match authenticated user sessions

Monitoring Recommendations

• Enable detailed logging on collection management endpoints
• Configure alerts for high-volume collection modification requests from single sessions
• Implement user behavior analytics to detect accounts performing operations on multiple other users' collections
• Review application logs periodically for authorization bypass indicators

How to Mitigate CVE-2026-28354

Immediate Actions Required

• Upgrade ClipBucket v5 to version 5.5.3 #59 or later immediately
• If immediate patching is not possible, consider temporarily disabling collection management features
• Audit recent collection modifications for signs of unauthorized access
• Review user accounts for suspicious activity patterns

Patch Information

The vulnerability has been addressed in ClipBucket v5 version 5.5.3 #59. The patch implements proper authorization checks in the add_to_collection.php script and fixes the broken ownership verification in the removeItemFromCollection() function. For detailed information about the security fix, refer to the GitHub Security Advisory GHSA-6wf8-rw5f-c9mv.

Workarounds

• Restrict access to collection management endpoints at the web server level using IP-based access controls
• Implement additional authorization middleware to validate collection ownership before processing requests
• Temporarily disable collection sharing and management features until patching is complete
• Deploy WAF rules to monitor and potentially block suspicious requests to affected endpoints

# Example: Restrict access to vulnerable endpoints via Apache .htaccess
<Files "add_to_collection.php">
    # Restrict to trusted IP ranges until patched
    Require ip 192.168.1.0/24
</Files>

<Location "/manage_collections.php">
    # Add additional access logging
    SetEnvIf Request_URI "mode=manage_items" collection_access
    CustomLog /var/log/apache2/collection_access.log combined env=collection_access
</Location>