CVE-2026-9643

WP Meta SEO <= 4.5.18 - Unauthenticated Stored Cross-Site Scripting via REQUEST_URI in 404 Logging

2026-06-23 16:46
zedeq

Strategic Overview

Status
Unpatched
Affected Plugin
WP Meta SEO
Affected Version
<= 4.5.18
CVSS
7.2High
Weakness type
CWE-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CVE
CVE-2026-9643
View all WP Meta SEO vulnerabilities

At a glance

CVE-2026-9643 is a high-severity Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in the WP Meta SEO WordPress plugin, affecting versions <= 4.5.18. It carries a CVSS score of 7.2 (reachable over the network; low attack complexity). Exploitation requires no authentication. No fixed release has been reported yet; treat installations running this software as exposed. Disclosed June 2026, reported by zedeq.

Vulnerability Overview

The WP Meta SEO plugin for WordPress is vulnerable to Unauthenticated Stored Cross-Site Scripting via the REQUEST_URI server variable in all versions up to, and including, 4.5.18. When the plugin's `wpmsTemplateRedirect()` hook detects a 404, it concatenates `$_SERVER['HTTP_HOST']` with the raw `$_SERVER['REQUEST_URI']` and inserts that value verbatim into the `wp_wpms_links.link_url` column via `$wpdb->insert()`. This makes it possible for unauthenticated attackers to inject arbitrary web scripts that execute whenever an administrator views the plugin's 404 & Redirects admin page (`/wp-admin/admin.php?page=metaseo_broken_link`).

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.

CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

WP Meta SEO <= 4.5.18 carries this weakness at HTTP_HOST, and reaching it takes no account at all. Cross-site scripting happens when input from a request is written into a page without being escaped for the context it lands in, so the browser parses attacker-supplied text as markup or script.

Injected script runs with the privileges of whoever views the affected page, which is how these flaws turn into administrator session theft, silent account creation or persistent backdoors in page content. No fixed build of this plugin is recorded for WP Meta SEO yet, so installs running <= 4.5.18 stay exposed until the vendor ships one.

Remediation

No known patch available. Please review the vulnerability's details in depth and employ mitigations based on your organization's risk tolerance. It may be best to uninstall the affected software and find a replacement.

How does WordSec protect against this?

Requests carrying this pattern arrive without a session, so nothing upstream of the firewall gets a chance to reject them: WordSec's web application firewall inspects request payloads before WordPress loads them. No patched version is recorded yet, which is the case where a filtering layer matters most, because there is nothing to update to.

  • Firewall
  • Login Security
  • Alerts

External References

https://www.cve.org/CVERecord?id=CVE-2026-9643https://www.wordfence.com/threat-intel/vulnerabilities/id/beceb218-34bf-4571-a07b-939abc7ead8ehttps://nvd.nist.gov/vuln/detail/CVE-2026-9643

Related records

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