CVE-2026-30842: Wallos Auth Bypass Vulnerability

CVE-2026-30842 Overview

CVE-2026-30842 is an Insecure Direct Object Reference (IDOR) vulnerability affecting Wallos, an open-source, self-hostable personal subscription tracker. Prior to version 4.6.2, the application allows any authenticated user to delete avatar files uploaded by other users due to missing authorization checks in the avatar deletion endpoint.

The vulnerability exists because the avatar deletion functionality does not verify that the requested avatar belongs to the current user. As a result, any authenticated user who knows or can discover another user's uploaded avatar filename can delete that file, leading to unauthorized data manipulation.

Critical Impact

Authenticated attackers can delete arbitrary user avatar files, potentially disrupting user profiles and causing data integrity issues across the application.

Affected Products

• Wallos versions prior to 4.6.2
• wallosapp wallos (all installations running vulnerable versions)
• Self-hosted Wallos instances without the security patch

Discovery Timeline

• 2026-03-07 - CVE CVE-2026-30842 published to NVD
• 2026-03-11 - Last updated in NVD database

Technical Details for CVE-2026-30842

Vulnerability Analysis

This vulnerability is classified under CWE-862 (Missing Authorization). The core issue stems from the avatar deletion endpoint failing to implement proper ownership verification before processing file deletion requests. When a user attempts to delete an avatar, the application processes the request without confirming that the avatar file actually belongs to the requesting user's account.

The vulnerability requires authentication to exploit, meaning an attacker must have valid credentials to the Wallos application. However, once authenticated, even a low-privileged user can enumerate or guess avatar filenames belonging to other users and submit deletion requests for those files. The impact is primarily on data integrity, as attackers cannot read or modify the content of avatars—only delete them.

Root Cause

The root cause is the absence of authorization logic in the avatar deletion endpoint. The application accepts a filename parameter and proceeds to delete the specified file without performing an ownership check against the authenticated user's session. This is a classic Insecure Direct Object Reference (IDOR) pattern where direct object identifiers (in this case, filenames) are exposed without proper access control validation.

Attack Vector

The attack is network-based and requires low complexity to execute. An authenticated attacker can exploit this vulnerability by:

1. Authenticating to the Wallos application with valid credentials
2. Identifying or guessing the avatar filename of another user (potentially through enumeration or predictable naming patterns)
3. Sending a deletion request to the avatar endpoint with the target user's avatar filename
4. The server processes the request without ownership verification, deleting the victim's avatar

The vulnerability exploits missing server-side authorization checks. The avatar deletion endpoint accepts direct filename references without validating that the requesting user owns the specified file. An attacker with a valid session can craft requests targeting any avatar file on the system. For technical implementation details, see the GitHub Security Advisory.

Detection Methods for CVE-2026-30842

Indicators of Compromise

• Unexpected avatar deletions or missing profile images reported by users
• Unusual patterns in avatar deletion API calls, particularly from single user sessions targeting multiple avatar files
• Log entries showing avatar deletion requests for files not belonging to the authenticated user

Detection Strategies

• Monitor API logs for avatar deletion requests and correlate with user ownership records
• Implement anomaly detection for users attempting to delete multiple avatars in a short timeframe
• Review authentication logs for accounts making unusual numbers of requests to avatar-related endpoints
• Set up alerts for avatar deletion requests where the target filename does not match the authenticated user's profile

Monitoring Recommendations

• Enable detailed logging on avatar-related endpoints including filename parameters and authenticated user identifiers
• Implement rate limiting on avatar deletion endpoints to slow down enumeration attempts
• Deploy application-level monitoring to detect IDOR attack patterns across user-specific resources

How to Mitigate CVE-2026-30842

Immediate Actions Required

• Upgrade Wallos to version 4.6.2 or later immediately
• Review application logs for any evidence of unauthorized avatar deletions
• Audit user avatar files to identify any missing or unexpectedly deleted avatars
• Consider temporarily restricting avatar management functionality if immediate upgrade is not possible

Patch Information

The vulnerability has been patched in Wallos version 4.6.2. The fix implements proper authorization checks to ensure users can only delete their own avatar files. The security patch is available through the GitHub Commit and the GitHub Release v4.6.2.

For detailed information about the vulnerability and remediation, refer to the GitHub Security Advisory GHSA-qw24-3pxr-3j6r.

Workarounds

• Implement network-level access controls to restrict access to the Wallos application to trusted users only
• Deploy a web application firewall (WAF) with rules to detect and block IDOR attack patterns
• Limit user account creation to prevent unauthorized access to the application
• Monitor and audit all avatar-related API calls until the patch can be applied

# Configuration example - Upgrading Wallos to patched version
cd /path/to/wallos
git fetch --tags
git checkout v4.6.2
# Or if using Docker
docker pull wallos:4.6.2
docker-compose up -d