CVE-2026-5032
Information Exposure in W3 Total Cache Plugin via User-Agent Header
Publication date: 2026-04-02
Last updated on: 2026-04-08
Assigner: Wordfence
Description
Description
CVSS Scores
EPSS Scores
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| Percentile: |
Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| wordfence | w3_total_cache | to 2.9.3 (inc) |
| wordfence | w3_total_cache | 2.9.4 |
Helpful Resources
Exploitability
| CWE ID | Description |
|---|---|
| CWE-200 | The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information. |
Attack-Flow Graph
AI Powered Q&A
How can this vulnerability be detected on my network or system? Can you suggest some commands?
This vulnerability can be detected by sending HTTP requests to the WordPress site with a crafted User-Agent header containing "W3 Total Cache" and inspecting the page source for raw mfunc/mclude dynamic fragment HTML comments that include the W3TC_DYNAMIC_SECURITY security token.
A practical detection method is to use command-line tools like curl to send such requests and check the response for the presence of these dynamic fragment tags and security tokens.
- curl -H "User-Agent: W3 Total Cache" https://example.com/page | grep -i W3TC_DYNAMIC_SECURITY
- curl -H "User-Agent: W3 Total Cache" https://example.com/page | grep -E '<!--mfunc|<!--mclude'
If the response contains these raw dynamic fragment comments or the security token, it indicates the vulnerability is present and exploitable.
Can you explain this vulnerability to me?
The W3 Total Cache plugin for WordPress, in all versions up to and including 2.9.3, has a vulnerability that causes it to bypass its entire output buffering and processing pipeline when the HTTP request's User-Agent header contains the string "W3 Total Cache".
This bypass results in raw dynamic fragment HTML comments, including the sensitive W3TC_DYNAMIC_SECURITY security token, being rendered directly in the page source. Because of this, unauthenticated attackers can send a specially crafted User-Agent header to any page with developer-placed dynamic fragment tags and, if fragment caching is enabled, discover the value of the security token.
How can this vulnerability impact me? :
This vulnerability allows unauthenticated attackers to obtain the W3TC_DYNAMIC_SECURITY token by exploiting the User-Agent header bypass. Exposure of this security token can lead to unauthorized access to dynamic fragment cache features, potentially allowing attackers to manipulate or bypass caching mechanisms.
Since the vulnerability has a CVSS v3.1 base score of 7.5 with high confidentiality impact, it means sensitive information can be disclosed without requiring authentication, increasing the risk of further attacks or privilege escalation.
What immediate steps should I take to mitigate this vulnerability?
The immediate mitigation step is to update the W3 Total Cache plugin to version 2.9.4 or later, where the vulnerability has been addressed.
The update includes security improvements such as sanitizing user agent strings, refining output buffering to prevent bypass based on User-Agent, and removing the ability to leak the W3TC_DYNAMIC_SECURITY token.
Additionally, ensure that fragment caching is configured securely and consider disabling fragment caching if an immediate update is not possible.
Monitor and restrict access to the site to prevent unauthenticated attackers from sending crafted User-Agent headers.
How does this vulnerability affect compliance with common standards and regulations (like GDPR, HIPAA)?:
The vulnerability in the W3 Total Cache plugin exposes a security token (W3TC_DYNAMIC_SECURITY) through raw HTML comments when a crafted User-Agent header is used. This information exposure could potentially allow unauthenticated attackers to gain sensitive security tokens, which may lead to unauthorized access or manipulation of cached content.
Such exposure of security tokens and potential unauthorized access could impact compliance with data protection standards and regulations like GDPR and HIPAA, which require safeguarding sensitive information and ensuring proper access controls to prevent data breaches.
However, the provided context and resources do not explicitly discuss or analyze the direct impact of this vulnerability on compliance with these standards.