WordPress WooCommerce VAT Plugin Stored XSS via Header Injection

The European VAT Compliance Assistant for WooCommerce plugin for WordPress is vulnerable to Stored Cross-Site Scripting via CF-IPCountry Header in all versions up to, and including, 1.36.10 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. The malicious header value is persisted verbatim into order post-meta during a guest checkout, meaning no account or authentication is required to plant the payload.

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 European VAT Compliance Assistant plugin for WooCommerce contains a stored cross-site scripting (XSS) vulnerability that allows unauthenticated attackers to inject malicious JavaScript through the CF-IPCountry HTTP header. During guest checkout, this header value is unsanitized and persisted directly into order post-meta, creating a persistent attack vector. Any user—including site administrators and customers—who accesses an order containing the injected payload will execute the attacker's arbitrary scripts in their browser. This vulnerability affects all versions up to 1.36.10 and poses significant risk to WordPress e-commerce sites, as it enables credential theft, session hijacking, malware distribution, and complete compromise of customer data stored in WooCommerce orders.

Casky's 323 matching security skills detect this attack pattern by analyzing MITRE ATT&CK techniques TA0001 (Initial Access) and TA0043 (Reconnaissance). Practitioners using Casky with extended reasoning would identify suspicious CF-IPCountry header values containing script tags or encoded payloads in server logs and request telemetry, flag the persistence mechanism when malicious content is stored in order post-meta without sanitization, and correlate execution signals when stored XSS fires during order review workflows. The skill mapping reveals that sanitization bypasses (CWE-79) targeting e-commerce plugins represent a critical reconnaissance and initial access vector, allowing Casky to surface this vulnerability's attack surface before exploitation occurs in production environments.

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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-2026-100316.

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-2026-100316

Casky has 323 skills that investigate the attack patterns behind CVE-2026-100316. Run one and get CVSS-scored findings in 3 minutes.

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