CVE-2026-17532 PoC — Seraphinite Accelerator <= 2.29.18 - Reflected Cross-Site Scripting

Source

https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2026/CVE-2026-17532.yaml

Associated Vulnerability

Title: Seraphinite Accelerator <= 2.29.18 - Reflected Cross-Site Scripting (CVE-2026-17532)
Description: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.

Description

The Seraphinite Accelerator plugin for WordPress up to and including 2.29.18 was vulnerable to reflected cross-site scripting through the seraph_accel_prep parameter. CacheExtractPreparePageParams() compared the expected HMAC against the JSON-decoded nonce with PHP's loose != operator, so a JSON boolean true satisfied the comparison and bypassed the signature check, and _CbContentFinishSkip() then concatenated the attacker-controlled selfTest field straight into the response body, letting unauthenticated attackers inject arbitrary scripts.

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