CVE-2026-5032

W3 Total Cache <= 2.9.3 - Unauthenticated Security Token Exposure via User-Agent Header

2026-04-01 19:07
wesley (wcraft)

Strategic Overview

Status
Patched in 2.9.4
Affected Plugin
W3 Total Cache
Affected Version
<= 2.9.3
CVSS
7.5High
Weakness type
CWE-200 · Exposure of Sensitive Information to an Unauthorized Actor
CVE
CVE-2026-5032
View all W3 Total Cache vulnerabilities

At a glance

CVE-2026-5032 is a high-severity Exposure of Sensitive Information to an Unauthorized Actor vulnerability in the W3 Total Cache WordPress plugin, affecting versions <= 2.9.3. It carries a CVSS score of 7.5 (reachable over the network; low attack complexity; high confidentiality impact). Exploitation requires no authentication. The issue is fixed in version 2.9.4; sites on affected versions should update now. Disclosed April 2026, reported by wesley (wcraft).

Vulnerability Overview

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.

Technical Analysis

The vector marks this flaw as remotely reachable over the network, with low attack complexity — no special timing or configuration is needed, and no privileges on the target site, and no interaction from a victim user. A successful exploit has high impact on confidentiality.

CWE-200: Exposure of Sensitive Information to an Unauthorized Actor

Reaching this weakness in W3 Total Cache <= 2.9.3 takes no account at all. Sensitive information exposure means data the application intended to keep internal is returned to a caller who should not be able to see it.

The disclosed data — credentials, tokens, customer records or internal paths — is usually worth more as material for a follow-up attack than as an end in itself. For W3 Total Cache the fix is 2.9.4: builds <= 2.9.3 are affected, anything from 2.9.4 onward is not.

Remediation

Update to version 2.9.4, or a newer patched version

How does WordSec protect against this?

This one needs no account at all, which puts it outside what login hardening can reach; WordSec's login security narrows the account-level paths around it, and the firewall is what inspects the request itself. None of that substitutes for the fix: W3 Total Cache 2.9.4 closes this, and updating the plugin is the step that ends it.

  • Login Security
  • Alerts

External References

https://www.cve.org/CVERecord?id=CVE-2026-5032https://www.wordfence.com/threat-intel/vulnerabilities/id/a65eb62d-847b-4f3a-848b-1290e3118c01https://nvd.nist.gov/vuln/detail/CVE-2026-5032

Related records

Vulnerability data © Defiant, Inc., provided under the Wordfence Intelligence T&C