What the vulnerability does
01Description
The Seraphinite Accelerator plugin for WordPress is vulnerable to Reflected Cross-Site Scripting via the 'seraph_accel_prep' parameter in versions up to, and including, 2.29.15. This is due to the CacheExtractPreparePageParams() function using PHP's loose inequality operator (!=) to compare the expected HMAC string against the JSON-decoded 'nonce' value — supplying the JSON boolean true causes any non-empty HMAC string to compare as loosely equal, bypassing the signature check — combined with insufficient output escaping in the _CbContentFinishSkip() function, which concatenates the attacker-controlled 'selfTest' field directly into the HTML response body. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that execute if they can successfully trick a user into performing an action such as clicking on a specially crafted link.
Explanation of Vulnerability in Simple Terms
02Summary
Seraphinite Accelerator versions 2.29.18 and earlier contain a cross-site scripting (XSS) vulnerability. An attacker can inject malicious scripts that execute in a victim's browser when they visit an affected page. The vulnerability requires user interaction and can affect other users or the site itself depending on where the injection occurs.
What an attacker can do
03Attacker Capabilities
Inject malicious scripts that run in visitors' browsers, potentially stealing session tokens or redirecting users.
Potential impact on your site
04Site Impact
Visitors to your site could be redirected, have their sessions hijacked, or see malicious content injected into pages.
Conditions required to exploit
05Prerequisites
Victim must visit a page containing the attacker's malicious input; no authentication required.
Key dates
06Disclosure timeline
August 5, 2026
CVE published
