CVE-2026-4351 Perfmatters <= 2.5.9 - Authenticated (Subscriber+) Arbitrary File Overwrite via 'snippets' Parameter
Authenticated attackers can overwrite arbitrary files via path traversal in the snippets parameter, potentially causing denial of service.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-4351?
CVE-2026-4351 is a high-severity path traversal vulnerability in Perfmatters, published on 10 Apr 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
The Perfmatters plugin for WordPress is vulnerable to arbitrary file overwrite via path traversal in all versions up to, and including, 2.5.9. This is due to the `PMCS::action_handler()` method processing the bulk action `activate`/`deactivate` handlers without any authorization check or nonce verification. The `$_GET['snippets'][]` values are passed unsanitized to `Snippet::activate()`/`Snippet::deactivate()` which call `Snippet::update()` then `file_put_contents()` with the traversed path. This makes it possible for authenticated attackers, with Subscriber-level access and above, to overwrite arbitrary files on the server with a fixed PHP docblock content, potentially causing denial of service by corrupting critical files like `.htaccess` or `index.php`.
Weakness: CWE-22
Which versions are affected by CVE-2026-4351?
How do I fix CVE-2026-4351?
No fix has been published for CVE-2026-4351 yet. Limit exposure of the affected software until one is available.
Upgrade, and resolve every user-supplied path against an allowed base folder before opening it. More about Path traversal.
Is CVE-2026-4351 being exploited?
There is no known exploitation of CVE-2026-4351 in the wild and no public exploit code.
Sources
Also known as GHSA-9m4j-jrjw-j2xh.