CVE-2026-13169: Eventin WordPress Auth Bypass Flaw

CVE-2026-13169 Overview

CVE-2026-13169 affects the Eventin WordPress plugin in versions prior to 4.1.21. The plugin fails to verify event ownership before permitting modification, deletion, or author reassignment. Authenticated users with contributor-level access or above can alter, delete, or take over events created by other users, including administrators. The flaw is classified as an Insecure Direct Object Reference [CWE-639].

Critical Impact
Contributor-level accounts can hijack administrator-owned events, resulting in unauthorized modification, deletion, and takeover of content across the WordPress site.

Affected Products

Eventin WordPress plugin versions before 4.1.21
WordPress sites permitting contributor-level (or higher) user registration
Multi-author WordPress environments using Eventin for event management

Discovery Timeline

2026-08-19 - CVE-2026-13169 published to the National Vulnerability Database
2026-08-19 - Last updated in NVD database

Technical Details for CVE-2026-13169

Vulnerability Analysis

The Eventin plugin exposes event management endpoints that accept an event identifier from the request and act on the corresponding record without confirming the caller owns the resource. Any authenticated user holding at least the contributor capability can supply an arbitrary event ID and trigger modification, deletion, or author reassignment. This breaks the WordPress multi-author trust model, where contributors are expected to interact only with their own content.

Because the vulnerability targets integrity and confidentiality of event data, an attacker can reassign an administrator-owned event to their own account and then edit its content freely. Deletion of live events also disrupts published site functionality.

Root Cause

The root cause is a missing authorization check on event object references. The affected handlers validate authentication and general capability but do not compare the event's stored author ID to the current user ID. This is the canonical pattern described by CWE-639: Authorization Bypass Through User-Controlled Key.

Attack Vector

Exploitation requires an authenticated session with contributor privileges or higher and network access to the WordPress admin or REST endpoints exposed by Eventin. The attacker submits a crafted request referencing an event ID they do not own. The plugin processes the request and applies the change under the target event's context. No user interaction from the victim is required.

For technical specifics, see the WPScan Vulnerability Report.

Detection Methods for CVE-2026-13169

Indicators of Compromise

Event records whose post_author value has changed without a corresponding administrator action in the WordPress audit log.
Unexpected deletions or edits of events originally authored by administrators or editors.
Contributor accounts issuing POST or DELETE requests against Eventin REST routes referencing event IDs they did not create.

Detection Strategies

Review WordPress database post_author history for the eventin custom post type and flag ownership transitions between low-privilege and high-privilege users.
Inspect web server access logs for requests to Eventin endpoints (for example paths containing /wp-json/eventin/ or admin-ajax.php with Eventin actions) originating from contributor sessions.
Correlate contributor logins with subsequent event modification events in the audit trail.

Monitoring Recommendations

Enable a WordPress activity logging plugin to capture user, action, and object identifiers for every event change.
Alert on any bulk deletion or author reassignment of the eventin post type.
Monitor for privilege-tier mismatches where a contributor modifies content authored by an administrator.

How to Mitigate CVE-2026-13169

Immediate Actions Required

Upgrade the Eventin plugin to version 4.1.21 or later on all WordPress sites.
Audit existing contributor and author accounts and remove any that are unused or unrecognized.
Review recent event modifications and restore any records that were altered or reassigned without authorization.

Patch Information

The vendor addressed the missing ownership check in Eventin 4.1.21. Updating through the WordPress plugin manager to 4.1.21 or later resolves the vulnerability. Refer to the WPScan Vulnerability Report for advisory details.

Workarounds

If immediate patching is not possible, temporarily deactivate the Eventin plugin until the update is applied.
Restrict event management capabilities by removing contributor and author roles from untrusted users.
Place the WordPress admin and REST API behind an IP allowlist or authenticated reverse proxy to limit exposure.

bash

# Update Eventin via WP-CLI to the patched release
wp plugin update wp-event-solution --version=4.1.21

# Verify installed version
wp plugin get wp-event-solution --field=version