CVE-2026-11354 Overview
The Participants Database plugin for WordPress contains a missing authorization flaw [CWE-862] that exposes stored participant data to unauthenticated attackers. All versions up to and including 2.7.8.3 accept an arbitrary id parameter on the public submission handler. Attackers can overwrite any participant record by numeric ID and redirect the private_id-bearing record-access link to an attacker-controlled email address. This grants full read and edit access to personally identifiable information (PII) including names, email addresses, phone numbers, and any other fields collected in the database.
Critical Impact
Unauthenticated attackers can hijack any participant record and receive the private access link in an attacker-controlled mailbox, exposing stored PII.
Affected Products
- Participants Database plugin for WordPress, versions through 2.7.8.3
- WordPress sites rendering the plugin's public signup or record shortcodes
- Any deployment collecting PII through the affected shortcode forms
Discovery Timeline
- 2026-07-24 - CVE-2026-11354 published to NVD
- 2026-07-24 - Last updated in NVD database
Technical Details for CVE-2026-11354
Vulnerability Analysis
The vulnerability resides in the plugin's public submission handler, which processes action=update and action=retrieve requests without validating whether the requester owns the referenced record. The handler trusts the id parameter supplied in the POST body and uses it directly in the update query. An unauthenticated attacker can substitute any numeric record ID and modify the associated fields, including the contact email that receives the private_id link.
Because the flaw exposes confidentiality of stored personal data through an integrity violation, it maps to Missing Authorization [CWE-862]. The plugin's nonce control does not enforce per-record authorization, so a nonce harvested from a public form applies to any record.
Root Cause
The root cause is missing authorization on the record update and retrieval endpoints. The submission logic in PDb_Shortcode.php and the update query in update_query.php do not verify that the requesting session owns the record referenced by id. Nonce verification is treated as sufficient, but nonces are readily obtainable from any page that renders the public shortcode.
Attack Vector
An attacker first issues an unauthenticated GET request to any page rendering the public signup or record form to harvest a valid WordPress nonce. The attacker then submits a POST request with action=update, an arbitrary numeric id, and an attacker-controlled email address. A follow-up POST with action=retrieve triggers delivery of the private-access link to the attacker's mailbox. The attacker then uses the link to read and edit the victim's stored PII.
Technical references are available in the Wordfence Vulnerability Report and the WordPress Plugin Changeset Details.
Detection Methods for CVE-2026-11354
Indicators of Compromise
- Unauthenticated POST requests to the plugin's submission endpoint containing action=update with sequential or enumerated id values.
- Outbound plugin-generated emails delivering private_id record links to addresses that do not match the original participant record.
- Unexpected modifications to participant email fields immediately preceding action=retrieve requests from the same source IP.
Detection Strategies
- Review web server access logs for POST requests targeting the Participants Database submission handler paired with prior GET requests to pages hosting the signup or record shortcode.
- Monitor the plugin's audit or change history, if enabled, for record updates originating without an authenticated user context.
- Correlate outbound mail logs against participant record change events to identify redirected private_id deliveries.
Monitoring Recommendations
- Enable verbose logging on WordPress and forward events to a centralized analytics platform for anomaly review.
- Alert on rapid enumeration of the id parameter from a single client IP or user agent.
- Track email address changes on participant records and flag any change immediately followed by a record retrieval action.
How to Mitigate CVE-2026-11354
Immediate Actions Required
- Update the Participants Database plugin to a version later than 2.7.8.3 as soon as the vendor releases a fixed build.
- Audit existing participant records for unauthorized email address changes and revert affected entries.
- Rotate private_id values for any records that show signs of tampering to invalidate previously distributed access links.
Patch Information
Refer to the WordPress Plugin Changeset Details for the code changes associated with this issue. Administrators should upgrade to the first plugin release published after version 2.7.8.3. Verify that the fix enforces per-record authorization on both action=update and action=retrieve.
Workarounds
- Temporarily unpublish or restrict pages that render the plugin's public signup or record shortcodes until a patched release is installed.
- Deploy a Web Application Firewall (WAF) rule to block unauthenticated POST requests containing action=update to the plugin endpoint.
- Require authentication (for example via an access-control plugin) on pages that host Participants Database shortcodes to eliminate anonymous nonce harvesting.
# Example WAF rule (ModSecurity-style) to block anonymous update actions
SecRule REQUEST_METHOD "@streq POST" \
"chain,phase:2,deny,status:403,id:2026113540,\
msg:'Block anonymous Participants Database update'"
SecRule ARGS:action "@streq update" "chain"
SecRule REQUEST_HEADERS:Cookie "!@rx wordpress_logged_in_"
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
