WordPress security changelog
HIGH CVE-2026-4351 Deferred

Perfmatters: Filesystem traversal

Perfmatters is affected by filesystem traversal. Exploitation requires at least subscriber-level access. A crafted path can escape the intended directory and reach files or directories elsewhere on the server. The published affected range is <= 2.5.9.

CVE / CNA score 8.1 CVSS 3.1 · security@wordfence.com
NVD score Pending NVD has not published its own CVSS assessment.
Component
Perfmatters
Plugin slug
perfmatters
Affected
<= 2.5.9
Safe version
> 2.5.9
Published
Apr 10, 2026
Weakness
CWE-22 — Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

This CVE was published Apr 10, 2026 and is one of 9 known issues for this plugin.

Update, patch or deactivate.

Update Perfmatters to a release after 2.5.9, or disable and remove it until a fixed version is available.

A safe version is available, so updating to that version or later is the preferred remediation. If an immediate update is not practical, consider a targeted application patch or temporarily restricting the affected functionality.

Deactivate only when warranted by your risk profile, or when advised by your hosting provider in the limited circumstances where the vulnerability cannot otherwise be mitigated. If you’re unsure which action is appropriate, contact Fused or your hosting provider for guidance.

Technical 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`.

CVE / CNA vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H

Primary and upstream sources