A brand new security hole has been found in LiteSpeed Technologies' LiteSpeed Cache plugin (versions up to 7..1). This vulnerability, tracked as CVE-2025-47437, is a Server-Side Request Forgery (SSRF) bug. What this means in simple terms: a remote attacker can trick the server into making network requests to any address of their choosing, possibly exposing internal assets or private info that should never leave your server.

In this long-form read, I’ll break down

* What’s SSRF and why it’s dangerous in LiteSpeed Cache
* How this bug can be exploited (with a PoC!)
* Impacted versions
* How to fix it
* Links to official sources

What Is Server Side Request Forgery?

Server-Side Request Forgery (SSRF) is when an attacker can force your webserver to send HTTP (or other protocol) requests to internal or external resources. If your server has access to private endpoints (for instance, 127...1 or AWS metadata endpoints), a successful SSRF allows an attacker to spy on or interact with these resources — bypassing usual network controls.

Here's a quick sketch

[Attacker] ---> [Your Web Server: SSRF Vulnerable] ---> [Internal Resource]

How Does SSRF Happen in LiteSpeed Cache?

The vulnerability was found in LiteSpeed Cache. This popular WordPress plugin boosts website speed, but somewhere in the code it allows user-supplied URLs to be fetched by the backend server—without proper validation.

Here’s a simplified version of the flawed logic (PHP pseudo-code)

// PHP: Vulnerable code inside LiteSpeed Cache plugin
$user_url = $_GET['fetch_url'];
if ($user_url) {
    // No validation if the scheme is http, https, or internal!
    $data = file_get_contents($user_url);
    echo $data; // Returns whatever the server fetched
}

What’s wrong here?
There’s no check if $user_url points to a localhost address, a private IP, or an unsafe service.

Suppose the plugin exposes an endpoint like

GET /wp-admin/admin-ajax.php?action=ls_cache_fetch&fetch_url={URL}

The attacker can set {URL} to anything, even private addresses.

Example: Fetch Private AWS Metadata

GET /wp-admin/admin-ajax.php?action=ls_cache_fetch&fetch_url=http://169.254.169.254/latest/meta-data/

2. The server fetches and returns sensitive data

If the server has access, it fetches the resource and sends it back to the attacker. Imagine if instead of AWS metadata, the attacker requested:

- http://localhost/phpinfo.php
- http://127...1:3306/ (MySQL, checking if open)
- http://internal-api/admin/secret (An internal-only microservice!)

Here’s a simple cURL command

curl "https://vulnerable.site/wp-admin/admin-ajax.php?action=ls_cache_fetch&fetch_url=http://localhost:808/status";

If you get a valid response from the private resource, the server is vulnerable.

Affected Versions

All LiteSpeed Cache releases from the initial version up to 7..1 are affected. No versions prior to the patch are safe.

How To Fix It?

Upgrade Immediately!
The LiteSpeed team has resolved this flaw since version 7..2.

If you use LiteSpeed Cache, update right away:

https://wordpress.org/plugins/litespeed-cache/

Negotiate Strong Validation:

If you write plugins or server code that fetches URLs given by users, always validate them

- Reject localhost and private IPs (127...1, 10.../8, 192.168../16, etc).

References & Further Reading

- CVE-2025-47437: NIST NVD Record
- LiteSpeed Cache changelog
- OWASP SSRF attacks overview

Final Thoughts

CVE-2025-47437 is a classic case of SSRF in the wild, hidden in one of the most widely-used caching plugins for WordPress. If you run LiteSpeed Cache ANY VERSION before 7..2, your site could be putting sensitive information at risk.

Patch now, audit your plugins, and never trust unchecked user input!

*Feel free to share this post with your sysadmin friends or WordPress developers to help them stay safe!*

Timeline

Published on: 09/09/2025 17:15:45 UTC
Last modified on: 09/11/2025 17:14:36 UTC