Relevanssi Premium Plugin Stored XSS via Click-Tracking Parameter

The Relevanssi Premium plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the '_rt' parameter in all versions up to, and including, 2.31.4 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. This requires the click-tracking and logging feature to be activated in the plugin settings, and exploitation is trivially accessible to unauthenticated users because a valid _rt_nonce is publicly emitted on every search-results page.

Casky was already ahead

This CVE exploits attack patterns that Casky's 323matched skills already investigate — long before this vulnerability was disclosed. Claude's reasoning model maps these techniques to MITRE ATT&CK, so practitioners who ran these skills have already seen the threat behaviour in their findings.

Analysis

Relevanssi Premium for WordPress contains a Stored Cross-Site Scripting vulnerability in the '_rt' parameter that affects all versions through 2.31.4. This vulnerability allows unauthenticated attackers to inject malicious scripts that persist in the database and execute in the browsers of any user viewing affected pages. The attack requires the click-tracking and logging feature to be enabled—a common configuration for analytics. With a CVSS score of 7.2, this poses a significant risk to WordPress sites relying on this popular search plugin, as successful exploitation can lead to session hijacking, credential theft, malware distribution, or defacement affecting all site visitors.

Casky.ai maps this vulnerability across 323 security skills tied to MITRE ATT&CK initial access and execution tactics (TA0001, TA0043). Practitioners using Casky's Claude-powered analysis would detect attack patterns including insufficient input sanitization (CWE-79 indicator) and missing output encoding in the '_rt' parameter handling. The platform would flag detection signals such as: unauthenticated script injection attempts in HTTP request parameters, stored payloads in WordPress plugin data, and script execution in user sessions post-injection. Security teams would receive findings highlighting the stored XSS attack chain—from initial exploitation requiring no authentication, through persistence in the database, to execution across victim browsers—enabling rapid identification of compromised installations and remediation of injected content before widespread impact occurs.

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Casky Risk Score

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EPSS Probability

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Shodan Exposure

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GreyNoise Signal

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Composite risk scoring from EPSS, CISA KEV, Shodan, and GreyNoise — 21 security APIs correlated into a single Casky Risk Score. Coming in Casky Pro. Join early access →

323 Casky skills cover this attack pattern

These skills use Claude AI's reasoning model to surface findings in the same attack categories as CVE-2026-103426.

Abuse of Public-Facing API: Mobile API Abuse

mobile security · low

Run

abusing-dpapi-for-credential-access

red teaming · high

Run

abusing-shadow-credentials-for-privesc

red teaming · high

Run

MITRE ATT&CK Techniques

TA0001 TA0043

Investigate the attack patterns behind CVE-2026-103426

Casky has 323 skills that investigate the attack patterns behind CVE-2026-103426. Run one and get CVSS-scored findings in 3 minutes.

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