The Rapid Cache plugin for WordPress (megaoptim) versions up to 1.2.3 suffers from a cache poisoning vulnerability (CWE-524) because it stores HTTP headers in cached data without proper sanitization. This flaw enables unauthenticated attackers to inject malicious HTTP headers into the cache, potentially leading to Cross-Site Scripting (XSS) attacks. The vulnerability has a CVSS 3.1 base score of 7.2, reflecting network attack vector, low attack complexity, no privileges or user interaction required, and impacts confidentiality and integrity with scope change. No patch or official fix is currently available, and no exploits have been observed in the wild.

An attacker can poison the cache with malicious HTTP headers, which may be unsanitized, resulting in Cross-Site Scripting (XSS). This can compromise confidentiality and integrity of affected web applications using the Rapid Cache plugin. The vulnerability is exploitable remotely without authentication and requires no user interaction, increasing risk. However, no known active exploitation has been reported.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is released, consider disabling the Rapid Cache plugin or restricting access to cached content to trusted users only. Monitor official megaoptim communications for updates on patches or temporary mitigations.