WordPress SiteOrigin CSS Plugin Stored DOM XSS

The SiteOrigin CSS plugin for WordPress is vulnerable to Stored DOM-Based Cross-Site Scripting via the 'url (comment_author_url)' parameter in all versions up to, and including, 1.6.7 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 is possible because WordPress core's esc_url() preserves HTML entity-encoded characters, allowing a crafted entity-encoded payload in the comment 'Website' field to survive storage and be DOM-decoded by the browser into executable markup at the sink.

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

The SiteOrigin CSS plugin for WordPress contains a Stored DOM-Based Cross-Site Scripting (XSS) vulnerability in versions up to 1.6.7, affecting the comment_author_url parameter. This vulnerability exists because the plugin fails to properly sanitize user input and escape output, relying on WordPress's esc_url() function which preserves HTML entity-encoded characters—allowing attackers to bypass protections. Unauthenticated attackers can inject malicious JavaScript that persists in the database and executes whenever any user accesses an affected page, potentially leading to session hijacking, credential theft, malware distribution, or defacement. With a CVSS score of 7.2 (high), this affects all WordPress installations using the vulnerable plugin versions, impacting both site administrators and regular visitors.

Casky's 323 matched skills map detection patterns across MITRE ATT&CK's TA0001 (Initial Access) and TA0043 (Reconnaissance) techniques, enabling practitioners to identify exploitation attempts and reconnaissance activity. Claude AI with extended reasoning analyzes how attackers probe for vulnerable plugin versions, craft payload encoding to bypass esc_url() protections, and monitor comment sections for successful injection confirmation. Practitioners using Casky would detect anomalies such as unusual comment submissions with encoded HTML entities in URLs, unexpected script execution in DOM contexts tied to user-supplied data, and access patterns suggesting post-infection reconnaissance. By correlating these signals against the CWE-79 (Improper Neutralization of Input During Web Page Generation) framework, security teams can pinpoint exploitation attempts targeting this specific sanitization weakness before malicious payloads reach end users.

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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-2026-107764.

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-2026-107764

Casky has 323 skills that investigate the attack patterns behind CVE-2026-107764. Run one and get CVSS-scored findings in 3 minutes.

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