WordPress security changelog
MEDIUM CVE-2026-17532 Deferred

Seraphinite HMAC type juggling exposes unauthenticated reflected XSS

Seraphinite Accelerator through 2.29.18 accepts seraph_accel_prep JSON in which the attacker supplies boolean true as nonce. CacheExtractPreparePageParams() uses a loose comparison against the expected HMAC, so the boolean can compare equal to a non-empty signature. The attacker-controlled selfTest value then reaches _CbContentFinishSkip(), which concatenates it into the HTML response without escaping, producing reflected JavaScript execution when a victim follows a crafted link. The CNA does not disclose the public route. Its prose stops at 2.29.15, but the structured affected data includes 2.29.18 and the linked fix follows that later tag.

CVE / CNA score 6.1 CVSS 3.1 · security@wordfence.com
NVD score Pending NVD has not published its own CVSS assessment.
Component
Seraphinite Accelerator
Plugin slug
seraphinite-accelerator
Affected
<= 2.29.18
Safe version
> 2.29.18
Published
Aug 05, 2026
Weakness
CWE-79 — Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

This CVE was published Aug 05, 2026 and is one of 11 known issues for this plugin.

What to do

Update, patch or deactivate.

Update Seraphinite Accelerator to a release after 2.29.18. The authoritative record links a trunk correction but does not identify the first fixed release. Avoid untrusted seraph_accel_prep links and review requests containing boolean nonce values or unexpected selfTest content.

A safe version is available, so updating to that version or later is the preferred remediation. If an immediate update is not practical, consider a targeted application patch or temporarily restricting the affected functionality.

Deactivate only when warranted by your risk profile, or when advised by your hosting provider in the limited circumstances where the vulnerability cannot otherwise be mitigated. If you’re unsure which action is appropriate, contact Fused or your hosting provider for guidance.

Source record

Technical 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.

CVE / CNA vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

References

Primary and upstream sources