WordPress XSS2Shell Flaw Chains Pre-Auth Login XSS to PHP Remote Code Execution

August 7, 2026

A critical vulnerability chain in WordPress Core, tracked as CVE-2026-64638 and nicknamed XSS2Shell, that turns a single failed login attempt into full remote code execution on the underlying server.

Because the flaw sits in code that has shipped with WordPress since version 4.7, it touched effectively every actively maintained installation of the world’s most popular content management system, which powers more than 43% of all websites on the internet, putting an estimated 500 million-plus sites at risk before a fix landed.

The chain begins on the ordinary login page, wp-login.php. When a username that does not exist is submitted, WordPress builds an error message using a sanitization function called wp_strip_all_tags.

Security researchers at pwn.ai have disclosed that inserting a space between the opening angle bracket and a tag name, such as “

That parser disagreement lets an attacker smuggle live, attacker-controlled elements like

,

, and

Original article can be found here