WordPress Broken Link Checker Plugin Stored XSS Flaw

The Broken Link Checker plugin for WordPress is vulnerable to Stored Cross-Site Scripting via Comment Author URL / Link Log in all versions up to, and including, 2.4.13 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. Exploitation requires an administrator to perform the plugin's standard dismiss-and-recheck workflow on a link submitted by the attacker via the WordPress comment author URL field, after which the attacker's HTTP server issues a redirect to a URL containing an HTML/JavaScript payload that is stored verbatim in the link log.

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

CVE-2026-75528 is a stored cross-site scripting (XSS) vulnerability in the WordPress Broken Link Checker plugin affecting all versions through 2.4.13. The vulnerability stems from insufficient input sanitization and output escaping in the Comment Author URL and Link Log functionality, allowing unauthenticated attackers to inject malicious scripts that persist in the database. When administrators perform the plugin's standard dismiss-and-recheck workflow, these scripts execute in the context of their browsers, potentially compromising administrative sessions, stealing credentials, or enabling lateral movement within WordPress installations. This is particularly dangerous because it requires no special privileges to inject—only that an administrator interact with the plugin's normal operations—making it a high-risk vector for widespread WordPress deployments that rely on this link-checking functionality.

Casky's skill set of 323 matching detections maps directly to MITRE ATT&CK techniques TA0001 (Initial Access) and TA0043 (Reconnaissance), enabling practitioners to identify attack patterns characteristic of this vulnerability class. Claude's extended reasoning capability allows Casky to correlate indicators such as: suspicious JavaScript payloads in comment author URL fields, unusual character encoding patterns designed to bypass sanitization filters, and timing correlations between link submissions and administrator activity logs. Practitioners would observe findings flagging unescaped user-controllable input flowing into page rendering contexts, malformed or obfuscated script tags in stored database records, and execution events triggered during admin panel interactions with the plugin's dismiss-recheck workflow. The platform's MITRE ATT&CK mapping helps teams understand that exploitation chains this vulnerability with reconnaissance activities (TA0043) to gather administrator behavior patterns before executing stored XSS payloads, positioning it as both an initial access and persistence mechanism within WordPress 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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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-2026-75528.

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-2026-75528

Casky has 323 skills that investigate the attack patterns behind CVE-2026-75528. Run one and get CVSS-scored findings in 3 minutes.

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