CVE-2026-57676 Overview
CVE-2026-57676 is an Insecure Direct Object Reference (IDOR) vulnerability in the Matteo Manna Simple User Avatar plugin for WordPress. The flaw affects all versions of Simple User Avatar up to and including 4.9. Attackers with low-privileged authenticated access can exploit incorrectly configured access control checks to manipulate user-controlled key parameters. This allows unauthorized read access to avatar-related resources belonging to other users. The vulnerability is classified under CWE-639: Authorization Bypass Through User-Controlled Key.
Critical Impact
Authenticated attackers can bypass authorization checks and access avatar data associated with other user accounts on affected WordPress installations.
Affected Products
- Matteo Manna Simple User Avatar plugin for WordPress
- All versions from initial release through 4.9
- WordPress sites with the plugin installed and active
Discovery Timeline
- 2026-06-29 - CVE-2026-57676 published to NVD
- 2026-06-29 - Last updated in NVD database
Technical Details for CVE-2026-57676
Vulnerability Analysis
The Simple User Avatar plugin fails to properly validate whether an authenticated user has authorization to access or modify avatar records identified by a user-supplied identifier. The plugin accepts a user ID or similar object reference from the request and processes it without confirming that the requesting user owns the referenced resource. This pattern is a classic Insecure Direct Object Reference (IDOR) issue.
An authenticated attacker with any registered account can substitute another user's identifier in the vulnerable request parameter. The server processes the request against the referenced account rather than the attacker's own account. The result is unauthorized disclosure of avatar metadata linked to arbitrary user accounts.
Root Cause
The root cause is missing server-side authorization enforcement. The plugin relies on the request-supplied key to determine which resource to return without cross-checking session identity against resource ownership. CWE-639 describes this exact class of defect.
Attack Vector
Exploitation requires network access to the WordPress site and a low-privileged authenticated session. The attacker submits an HTTP request to the vulnerable plugin endpoint and substitutes a target user identifier in the request parameter. No user interaction from the victim is required. Refer to the Patchstack Vulnerability Report for technical details on the affected request pattern.
Detection Methods for CVE-2026-57676
Indicators of Compromise
- Authenticated HTTP requests to Simple User Avatar plugin endpoints that reference user identifiers different from the requester's session user ID.
- Sequential or enumerated user ID values appearing in plugin request parameters, suggesting IDOR probing.
- Unexpected access patterns from low-privileged accounts (e.g., subscriber role) targeting administrative or other user records.
Detection Strategies
- Review WordPress access logs for requests to Simple User Avatar plugin routes containing user_id or equivalent parameters that do not match the session owner.
- Deploy Web Application Firewall (WAF) rules that correlate the authenticated session user with parameter values in plugin requests.
- Enable WordPress audit logging plugins to record avatar-related actions and flag cross-account access attempts.
Monitoring Recommendations
- Monitor for high-frequency plugin requests from single accounts iterating through user identifier ranges.
- Alert on any modification of avatar data where the target user ID differs from the acting user ID.
- Track failed and successful authenticated requests to /wp-admin/admin-ajax.php and REST endpoints associated with the plugin.
How to Mitigate CVE-2026-57676
Immediate Actions Required
- Identify all WordPress installations running Simple User Avatar version 4.9 or earlier and inventory affected sites.
- Deactivate the Simple User Avatar plugin on affected sites until a patched version is confirmed available and installed.
- Restrict user registration and audit existing low-privileged accounts for signs of abuse.
Patch Information
At the time of publication, the vendor advisory referenced in the Patchstack Vulnerability Report is the primary source for remediation guidance. Administrators should apply any updated release published after version 4.9 immediately upon availability.
Workarounds
- Disable the plugin entirely if avatar management is not business-critical.
- Apply WAF rules that reject plugin requests where the parameter user ID does not match the authenticated session user.
- Limit registration and reduce the number of low-privileged accounts that can reach the vulnerable endpoint.
# Configuration example - disable the plugin via WP-CLI until patched
wp plugin deactivate simple-user-avatar --all-sites
wp plugin status simple-user-avatar
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
