CVE-2026-78262: WP Project Manager Auth Bypass Vulnerability

CVE-2026-78262 Overview

CVE-2026-78262 is an unauthenticated PHP Object Injection vulnerability affecting the WP Project Manager WordPress plugin in versions up to and including 4.0.6. The flaw is tracked under [CWE-502: Deserialization of Untrusted Data]. Remote attackers can send crafted serialized payloads to a vulnerable WordPress site and trigger PHP object instantiation without authentication. When combined with a suitable gadget chain in the WordPress core or other installed plugins, the vulnerability can lead to remote code execution, arbitrary file operations, or full site takeover.

Critical Impact
Unauthenticated attackers can inject arbitrary PHP objects over the network, enabling potential remote code execution and complete compromise of the WordPress site.

Affected Products

WP Project Manager (wedevs-project-manager) WordPress plugin, versions <= 4.0.6
WordPress installations with the plugin active and network-reachable
Multisite WordPress deployments running any affected plugin version

Discovery Timeline

2026-08-24 - CVE-2026-78262 published to the National Vulnerability Database (NVD)
2026-08-27 - EPSS score recorded at 0.331% (25.6th percentile)
2026-08-27 - Last updated in NVD database

Technical Details for CVE-2026-78262

Vulnerability Analysis

WP Project Manager passes attacker-controlled input to a PHP deserialization routine such as unserialize() without validating that the input contains only expected data types. Because the plugin exposes an endpoint reachable without authentication, any remote client can submit crafted serialized data. When PHP processes that data, it reconstructs arbitrary object instances and invokes their magic methods, including __wakeup() and __destruct().

The risk depends on the pool of classes available at runtime. In a WordPress environment, core, themes, and other plugins provide many candidate classes that can be chained into a gadget. A gadget chain assembled from these classes can lead to file writes, SQL execution, or command execution under the web server user.

Root Cause

The root cause is unsafe deserialization of user-controlled input, categorized under [CWE-502]. The plugin trusts serialized data supplied through a request parameter and does not restrict allowed classes, enforce integrity checks, or replace unserialize() with a safer alternative such as json_decode().

Attack Vector

The attack is delivered over the network with low complexity and requires no privileges or user interaction. An attacker submits an HTTP request containing a serialized PHP payload to the vulnerable plugin endpoint. Refer to the Patchstack Vulnerability Report for the specific endpoint and parameter details.

The vulnerability manifests when the plugin invokes PHP deserialization on the attacker-supplied string. No exploit code is currently published, and the vulnerability is not listed in the CISA Known Exploited Vulnerabilities catalog.

Detection Methods for CVE-2026-78262

Indicators of Compromise

HTTP requests containing serialized PHP patterns such as O:, a:, or s: followed by class or property specifiers in request bodies or query parameters targeting WP Project Manager endpoints
Unexpected PHP processes spawning shell commands (sh, bash, python) from the web server user context
New or modified PHP files in wp-content/uploads/, wp-content/plugins/, or theme directories that were not created by an administrator
Outbound network connections from the web server to unfamiliar hosts shortly after requests to plugin endpoints

Detection Strategies

Inspect web server and WordPress access logs for POST requests to WP Project Manager routes that carry serialized object markers in parameters
Deploy a Web Application Firewall (WAF) rule that blocks request bodies containing PHP serialization signatures where they are not expected
Correlate authentication-free plugin requests with subsequent file changes or process executions on the host

Monitoring Recommendations

Enable PHP error and access logging and forward the logs to a central platform for retention and search
Monitor for changes to plugin, theme, and upload directories using file integrity monitoring
Alert on new administrator account creation, option changes, and cron job additions within WordPress

How to Mitigate CVE-2026-78262

Immediate Actions Required

Update WP Project Manager to a version later than 4.0.6 once the vendor releases a fix, or deactivate and remove the plugin until a patched release is available
Restrict network access to WordPress administrative and plugin endpoints where feasible using IP allowlisting
Audit the site for indicators of compromise, focusing on unexpected administrator accounts, modified core files, and unknown scheduled tasks

Patch Information

At the time of publication, the Patchstack Vulnerability Report is the authoritative reference. Administrators should track the plugin's release notes on WordPress.org for a fixed version and apply it as soon as it becomes available.

Workarounds

Remove or deactivate WP Project Manager on all sites until a fixed release is confirmed
Deploy WAF signatures that reject requests containing PHP serialized object payloads on plugin routes
Restrict PHP execution in the wp-content/uploads/ directory and enforce least privilege on the web server user account
Take a verified backup before remediation to preserve forensic evidence in case of prior compromise

bash

# Configuration example: Nginx rule to block serialized PHP payloads on plugin routes
location ~* /wp-content/plugins/wedevs-project-manager/ {
    if ($request_body ~* "(^|[^a-zA-Z0-9])O:[0-9]+:\"") {
        return 403;
    }
    if ($args ~* "(^|[^a-zA-Z0-9])O:[0-9]+:%22") {
        return 403;
    }
}