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

• Severity: medium (CVSS 6.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.8% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-08-05 · updated 2026-08-12
• Weakness: CWE-79

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.

Affected products

• seraphinitesoft Seraphinite Accelerator: through 2.29.18

References

• https://plugins.trac.wordpress.org/browser/seraphinite-accelerator/tags/2.29.15/cache.php#L76
• https://plugins.trac.wordpress.org/browser/seraphinite-accelerator/tags/2.29.15/cache_ex.php#L838
• https://plugins.trac.wordpress.org/browser/seraphinite-accelerator/tags/2.29.15/common.php#L6036
• https://plugins.trac.wordpress.org/browser/seraphinite-accelerator/tags/2.29.18/cache.php#L76
• https://plugins.trac.wordpress.org/browser/seraphinite-accelerator/tags/2.29.18/cache_ex.php#L838
• https://plugins.trac.wordpress.org/browser/seraphinite-accelerator/tags/2.29.18/common.php#L6036
• https://plugins.trac.wordpress.org/changeset?sfp_email=&sfph_mail=&reponame=&new=3624461%40seraphinite-accelerator%2Ftrunk%2Fcache_ex.php&old=3619618%40seraphinite-accelerator%2Ftrunk%2Fcache_ex.php&sfp_email=&sfph_mail=
• https://plugins.trac.wordpress.org/changeset?sfp_email=&sfph_mail=&reponame=&new=3624461%40seraphinite-accelerator%2Ftrunk%2Fcommon.php&old=3619618%40seraphinite-accelerator%2Ftrunk%2Fcommon.php&sfp_email=&sfph_mail=
• https://www.wordfence.com/threat-intel/vulnerabilities/id/5aeea62b-bd6c-4fe2-8c0f-8c9919688e87?source=cve

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