CVE-2026-5032 PoC — W3 Total Cache <= 2.9.3 - Unauthenticated Security Token Exposure via User-Agent Header

Source

https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2026/CVE-2026-5032.yaml

Associated Vulnerability

Title: W3 Total Cache <= 2.9.3 - Unauthenticated Security Token Exposure via User-Agent Header (CVE-2026-5032)
Description:The W3 Total Cache plugin for WordPress is vulnerable to information exposure in all versions up to, and including, 2.9.3. This is due to the plugin bypassing its entire output buffering and processing pipeline when the request's User-Agent header contains "W3 Total Cache", which causes raw mfunc/mclude dynamic fragment HTML comments — including the W3TC_DYNAMIC_SECURITY security token — to be rendered in the page source. This makes it possible for unauthenticated attackers to discover the value of the W3TC_DYNAMIC_SECURITY constant by sending a crafted User-Agent header to any page that contains developer-placed dynamic fragment tags, granted the site has the fragment caching feature enabled. With the leaked W3TC_DYNAMIC_SECURITY token, an attacker can craft valid mfunc tags to execute arbitrary PHP code on the server, achieving remote code execution.

Description

The W3 Total Cache WordPress plugin through version 2.9.3 skips its entire output buffering and processing pipeline whenever an incoming request's User-Agent header contains the string "W3 Total Cache", without authenticating the caller. On sites that use developer-placed dynamic fragment tags, the raw mfunc/mclude HTML comments - which embed the per-site W3TC_DYNAMIC_SECURITY token - are therefore rendered directly into the page source instead of being processed and stripped, letting an unauthenticated attacker harvest the token by comparing a normal response against one sent with the magic User-Agent.

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