CVE-2026-16291 Overview
CVE-2026-16291 is an Insecure Direct Object Reference (IDOR) vulnerability [CWE-639] in the ProfileGrid WordPress plugin before version 5.9.9.8. The plugin fails to verify that a notification belongs to the requesting user before deletion. Any authenticated user, including a low-privileged Subscriber, can delete notifications belonging to other users by enumerating notification identifiers.
Critical Impact
Authenticated attackers with Subscriber-level access can delete arbitrary user notifications across the WordPress site, impacting the integrity of the notification system.
Affected Products
- ProfileGrid WordPress plugin versions prior to 5.9.9.8
- WordPress sites with user registration enabled that use ProfileGrid
- WordPress installations relying on ProfileGrid for community and membership features
Discovery Timeline
- 2026-08-02 - CVE-2026-16291 published to NVD
- 2026-08-04 - Last updated in NVD database
Technical Details for CVE-2026-16291
Vulnerability Analysis
The ProfileGrid plugin exposes an endpoint that processes notification deletion requests based on a supplied notification identifier. The endpoint authenticates the request but does not check whether the notification is owned by the requesting user. This missing ownership check enables horizontal privilege escalation against notification data.
An attacker authenticated as a Subscriber can iterate through numeric notification IDs and issue deletion requests for each one. Because notification identifiers are typically sequential integers, enumeration is straightforward. The impact is limited to integrity of the notification store; confidentiality and availability of other assets are not directly affected.
Root Cause
The root cause is a missing authorization check when handling notification deletion. The plugin trusts the client-supplied notification identifier and processes the delete action without validating that the current user owns the referenced notification. This pattern maps to CWE-639: Authorization Bypass Through User-Controlled Key.
Attack Vector
Exploitation requires a valid authenticated session at any privilege tier, including Subscriber, which is often the default role available through open WordPress registration. The attacker submits crafted HTTP requests to the notification deletion endpoint while varying the notification identifier parameter. No user interaction from the victim is required. See the WPScan Vulnerability Report for further technical detail.
Detection Methods for CVE-2026-16291
Indicators of Compromise
- Repeated authenticated POST or AJAX requests to ProfileGrid notification endpoints with sequential or enumerated ID values
- Users reporting missing notifications that were not dismissed by them
- Web server logs showing a single low-privileged account issuing high volumes of notification deletion actions
Detection Strategies
- Monitor WordPress access logs for bursts of requests from Subscriber accounts targeting ProfileGrid AJAX handlers
- Alert on any single authenticated session issuing deletion actions across a wide range of notification identifiers within a short interval
- Correlate WordPress database audit logs with user session data to identify cross-user notification deletions
Monitoring Recommendations
- Enable WordPress activity logging plugins to record notification deletion events with user context
- Forward web server and WordPress audit logs to a central log platform for retention and analysis
- Baseline normal notification deletion rates per user role and alert on deviations
How to Mitigate CVE-2026-16291
Immediate Actions Required
- Upgrade the ProfileGrid plugin to version 5.9.9.8 or later on all affected WordPress installations
- Audit existing Subscriber and low-privilege accounts for anomalous activity against notification endpoints
- Review WordPress registration settings and disable open registration where it is not required
Patch Information
The vendor addressed the missing ownership check in ProfileGrid version 5.9.9.8. Site administrators should apply the update through the WordPress plugin management interface or by deploying the patched package. Refer to the WPScan Vulnerability Report for the fixed release information.
Workarounds
- Temporarily disable the ProfileGrid plugin until the patched version can be deployed
- Restrict access to WordPress AJAX endpoints via web application firewall rules that block anomalous notification deletion patterns
- Remove or restrict the default Subscriber role from performing self-service actions until the update is applied
# Update ProfileGrid via WP-CLI
wp plugin update profilegrid-user-profiles-groups-and-communities --version=5.9.9.8
wp plugin list --name=profilegrid-user-profiles-groups-and-communities --fields=name,status,version
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
