WordPress Gutenberg Blocks Plugin Enables Authenticated Remote Code Execution

The Spectra Gutenberg Blocks – Website Builder for the Block Editor plugin for WordPress is vulnerable to Remote Code Execution in all versions up to, and including, 2.19.25. This makes it possible for authenticated attackers, with Contributor-level access and above, to execute code on the server. Exploitation requires a two-block payload embedded in post content: the first block registers a fake uagb/-prefixed block type with an attacker-specified render_callback, and the second block of the same fake type triggers invocation of that callback via call_user_func() during sequential block rendering in the same page request.

Casky was already ahead

This CVE exploits attack patterns that Casky's 203matched 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 Spectra Gutenberg Blocks plugin for WordPress contains a critical Remote Code Execution vulnerability affecting all versions through 2.19.25. Authenticated attackers with Contributor-level permissions or higher can execute arbitrary code on the server by embedding a two-block payload in post content. The first block registers a malicious block type with an attacker-controlled render_callback function, while the second block triggers its execution. This vulnerability is particularly dangerous because it requires only mid-level authentication access, making it accessible to a broader class of attackers on multi-user WordPress installations, and it directly impacts website administrators, agencies managing WordPress sites, and any organization using this popular page builder plugin.

Casky's 203 mapped security skills leverage Claude's extended reasoning to detect the Privilege Escalation (TA0004) attack patterns embedded in this vulnerability. Practitioners using the platform would observe detections focused on: (1) suspicious block type registration with dynamic callback functions, particularly those with uagb/ prefixes being registered outside normal plugin initialization; (2) post content analysis revealing multi-block payloads designed to chain functionality; and (3) privilege escalation signals where Contributor-level users trigger server-side code execution paths typically restricted to administrators. By mapping these indicators across MITRE ATT&CK techniques, Casky enables security teams to identify exploitation attempts in real-time, distinguishing legitimate block editor usage from adversarial payload injection, and providing the context needed to correlate post modifications with suspicious callback registrations.

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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 →

203 Casky skills cover this attack pattern

These skills use Claude AI's reasoning model to surface findings in the same attack categories as CVE-2026-7465.

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MITRE ATT&CK Techniques

TA0004

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