CVE-2026-27416 Overview
CVE-2026-27416 is a missing authorization vulnerability affecting the bPlugins PDF Poster plugin for WordPress. The flaw exists in versions up to and including 2.4.1 and stems from incorrectly configured access control security levels. Unauthenticated remote attackers can reach functionality that should require proper authorization checks. The issue is tracked under CWE-862: Missing Authorization.
The vulnerability allows attackers to exploit broken access control over the network without user interaction. Successful exploitation results in limited information disclosure from affected WordPress sites running the plugin.
Critical Impact
Unauthenticated network attackers can bypass access controls in PDF Poster 2.4.1 and earlier, leading to confidentiality impact on affected WordPress installations.
Affected Products
- bPlugins PDF Poster WordPress plugin
- Versions from n/a through 2.4.1
- WordPress sites with the vulnerable plugin installed and active
Discovery Timeline
- 2026-05-07 - CVE-2026-27416 published to NVD
- 2026-05-07 - Last updated in NVD database
Technical Details for CVE-2026-27416
Vulnerability Analysis
The PDF Poster plugin exposes one or more endpoints that fail to enforce proper authorization checks. The plugin should restrict sensitive operations to authenticated users with appropriate roles. Instead, the access control logic is misconfigured, allowing unauthenticated requests to reach protected functionality.
Missing authorization vulnerabilities in WordPress plugins typically appear in AJAX handlers, REST API endpoints, or admin-post actions. The plugin code registers these handlers but omits capability checks such as current_user_can() or nonce verification. Attackers send crafted HTTP requests directly to the vulnerable endpoint without authenticating.
The attack surface is reachable over the network with low complexity. No privileges or user interaction are required. The impact is limited to confidentiality, with no integrity or availability impact reported.
Root Cause
The root cause is incorrectly configured access control security levels within the plugin code. Capability checks and authorization validation are either missing or incorrectly implemented on protected endpoints. This maps to CWE-862, where authorization is not enforced when the application performs an action requiring specific privileges.
Attack Vector
Attackers craft HTTP requests targeting the vulnerable plugin endpoint on a WordPress site running PDF Poster 2.4.1 or earlier. The request reaches the handler without triggering authentication or authorization failures. The handler then returns data or performs an action that should have been restricted.
For exploitation specifics, refer to the Patchstack WordPress Vulnerability Report.
Detection Methods for CVE-2026-27416
Indicators of Compromise
- Unauthenticated HTTP requests to PDF Poster plugin endpoints under /wp-admin/admin-ajax.php or /wp-json/ routes registered by the plugin.
- Unexpected access to plugin-controlled resources from IP addresses without prior authentication sessions.
- Anomalous request volume targeting pdf-poster related actions or REST routes.
Detection Strategies
- Inventory all WordPress installations and identify sites running PDF Poster version 2.4.1 or earlier.
- Inspect web server access logs for requests to plugin endpoints originating from unauthenticated sessions.
- Deploy web application firewall rules that flag direct access to plugin AJAX or REST endpoints without valid authentication cookies.
Monitoring Recommendations
- Monitor WordPress audit logs for unusual plugin endpoint activity and unexpected data retrieval patterns.
- Track outbound responses from the affected endpoints for size anomalies that may indicate data exposure.
- Forward web server and WordPress logs to a centralized logging platform for correlation across hosts.
How to Mitigate CVE-2026-27416
Immediate Actions Required
- Identify all WordPress sites running the bPlugins PDF Poster plugin and confirm the installed version.
- Update PDF Poster to a version released after 2.4.1 that contains the access control fix.
- If a patched version is not yet available, deactivate and remove the plugin until a fix is published.
Patch Information
The vulnerability affects PDF Poster versions through 2.4.1. Site administrators should consult the Patchstack advisory and the WordPress plugin repository for the latest patched release. Apply the update through the WordPress admin dashboard or via WP-CLI.
Workarounds
- Deactivate the PDF Poster plugin until a patched version is installed.
- Restrict access to WordPress AJAX and REST endpoints using a web application firewall to block unauthenticated requests to plugin-specific actions.
- Apply virtual patching rules through Patchstack or equivalent WordPress security platforms to filter exploit attempts.
# Configuration example: identify and disable the vulnerable plugin via WP-CLI
wp plugin list --name=pdf-poster --fields=name,status,version
wp plugin deactivate pdf-poster
wp plugin update pdf-poster
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
