CVE-2026-17532

MEDIUM
Published Aug 5, 2026 Modified Aug 5, 2026 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.

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CVSS v3.1 Score

6.1
MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

EPSS — Exploit Prediction

0.0035
Probability of exploitation
0.27%
Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-79 Cross-site Scripting (XSS)

References

Other 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

Frequently Asked Questions

What is CVE-2026-17532? +
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. It has a CVSS v3.1 base score of 6.1 (MEDIUM).
How severe is CVE-2026-17532? +
CVE-2026-17532 has a CVSS v3.1 score of 6.1 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0035, placing it in the 0th percentile for exploitation probability.
How do I check if I'm vulnerable to CVE-2026-17532? +
You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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