WordPress Mapster Plugin Unauthenticated Stored XSS

The Mapster WP Maps plugin for WordPress is vulnerable to Stored Cross-Site Scripting in versions up to, and including, 2.0.5. This is due to the /wp-json/mapster-wp-maps/save-mapmaker REST route being registered with a permission_callback that unconditionally returns true (no capability check, no nonce), together with the mapster_write_config_to_acf() helper only sanitizing string config values with sanitize_text_field() — which strips HTML tags but leaves quote characters intact — and the mapster_wp_map shortcode renderer in mapster_wordpress_maps_shortcode_display() concatenating the stored loading_background_color value into a single-quoted inline style attribute without esc_attr(). This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected 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

The Mapster WP Maps plugin for WordPress versions up to 2.0.5 contains a critical stored cross-site scripting (XSS) vulnerability in its REST API endpoint. The /wp-json/mapster-wp-maps/save-mapmaker route lacks proper authentication checks—its permission_callback unconditionally returns true—allowing any unauthenticated attacker to inject malicious scripts. The vulnerability is compounded by insufficient input sanitization; while sanitize_text_field() strips HTML tags, it fails to escape quote characters, leaving the door open for attackers to break out of attribute contexts and inject arbitrary JavaScript. This affects all WordPress installations running the vulnerable plugin versions, particularly those exposed to untrusted networks. Once injected, the malicious payload persists in the database and executes in the browsers of site administrators and visitors, enabling credential theft, session hijacking, malware distribution, and complete site compromise.

Casky's skill set, powered by Claude AI's extended reasoning capabilities, maps this attack to MITRE ATT&CK techniques TA0001 (Initial Access) and TA0043 (Reconnaissance). Practitioners using Casky would identify detection patterns including: unauthenticated REST API calls to /wp-json/mapster-wp-maps/save-mapmaker endpoints with suspicious payloads containing script tags or event handlers, database modifications to map configuration fields containing unescaped JavaScript, and behavioral anomalies such as unusual administrative user-agent strings or requests originating from external IP ranges. The 323 mapped security skills enable Casky to correlate multiple indicators—detecting both the exploitation attempt (initial access vector) and the reconnaissance activities that often precede widespread attacks. Practitioners gain visibility into how attackers probe for vulnerable plugin versions, enumerate REST routes, and validate successful payload injection before scaling their attacks across multiple targets.

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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-2026-107743.

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-2026-107743

Casky has 323 skills that investigate the attack patterns behind CVE-2026-107743. Run one and get CVSS-scored findings in 3 minutes.

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