WordPress Plugin Improper HTML Sanitization in Comments

The Gutenverse News WordPress plugin before 3.3.3 does not restrict the extra HTML it adds to WordPress's allowed elements to the context it is meant for, applying the same relaxed list to every sanitisation context including untrusted comments, allowing unauthenticated users to store JavaScript that will execute in the browser of any administrator who reviews the comment queue, and of any visitor to the post once the comment is approved.

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-2026-85677 exposes a critical flaw in the Gutenverse News WordPress plugin where HTML sanitization rules are applied inconsistently across different contexts. The plugin maintains a relaxed whitelist of allowed HTML elements for legitimate use cases, but fails to restrict this permissive list when processing untrusted user input—specifically comments. This allows unauthenticated attackers to inject malicious JavaScript into comments, which persists in the database as stored XSS. The vulnerability affects all WordPress installations running the plugin before version 3.3.3, with two attack surfaces: administrators reviewing the comment queue execute the payload immediately, and site visitors see the malicious script once the comment is published. Given WordPress's ubiquity, this represents a significant supply chain risk affecting potentially thousands of websites.

Casky's 323 mapped skills detect the attack patterns underlying this vulnerability by analyzing MITRE ATT&CK techniques TA0001 (Reconnaissance) and TA0043 (Reconnaissance via Comment Exploitation). Using Claude's extended reasoning, the platform identifies the CWE-79 (Cross-site Scripting) signature across multiple attack phases: initial payload delivery through comment submission, persistence mechanisms as the malicious script stores in the database, and execution when administrators or visitors access affected pages. Practitioners using Casky would observe findings flagging improper input validation in sanitization routines, detection of JavaScript payloads bypassing HTML filters, and evidence of context-confusion patterns where admin-context rules leak into user-input contexts. The system would correlate these signals to highlight the stored XSS chain and recommend immediate patching, plus defensive measures like Content Security Policy headers and comment moderation workflows.

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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-2026-85677.

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-2026-85677

Casky has 323 skills that investigate the attack patterns behind CVE-2026-85677. Run one and get CVSS-scored findings in 3 minutes.

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