WordPress Royal MCP Plugin Reusable Preview Token Authentication Bypass

The Royal MCP WordPress plugin before 1.5.7 does not limit a preview-link token to the single preview it was issued for, so any party that obtains a valid token is authenticated as the token's owning user, an administrator in the default configuration, across the entire REST API with no nonce, leading to full site takeover.

Casky was already ahead

This CVE exploits attack patterns that Casky's 283matched 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 Royal MCP WordPress plugin before version 1.5.7 contains a critical authentication bypass vulnerability where preview-link tokens are not properly scoped to individual previews. An attacker who obtains a valid token can reuse it to authenticate as the token's owner across the entire REST API without requiring a nonce, typically granting administrator-level access and enabling full site takeover. This vulnerability affects any WordPress installation using the vulnerable plugin version, with particular risk to sites that rely on preview functionality for content collaboration. The attack requires no special privileges to discover or exploit a token once obtained, making it a high-impact vulnerability despite its straightforward exploitation.

Casky's 283 matched security skills leverage Claude AI's extended reasoning to detect the attack patterns associated with this vulnerability across MITRE ATT&CK's Initial Access (TA0004) and Credential Access (TA0006) techniques. Practitioners using Casky will observe detections for suspicious REST API authentication patterns, including repeated API calls from unusual sources using the same token credential, absence of expected nonce validation in WordPress REST requests, and privilege escalation indicators showing non-administrator accounts accessing admin-level endpoints. The platform's skill mapping would specifically highlight exploitation attempts that bypass CWE-287 (Improper Authentication) controls, flagging token reuse patterns that deviate from intended single-preview authorization, unusual API endpoint access sequences that indicate reconnaissance of administrative functions, and authentication succeeding without proper session context validation—all hallmarks of this token scope bypass attack.

Live Threat IntelligenceComing soon

Casky Risk Score

—

EPSS Probability

—

Shodan Exposure

—

GreyNoise Signal

—

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 →

283 Casky skills cover this attack pattern

These skills use Claude AI's reasoning model to surface findings in the same attack categories as CVE-2026-111958.

abusing-dpapi-for-credential-access

red teaming · high

Run

abusing-shadow-credentials-for-privesc

red teaming · high

Run

Access with Stolen Session Cookie

identity access management · low

Run

MITRE ATT&CK Techniques

TA0004 TA0006

Investigate the attack patterns behind CVE-2026-111958

Casky has 283 skills that investigate the attack patterns behind CVE-2026-111958. Run one and get CVSS-scored findings in 3 minutes.

Run the skill that detects this →

X Instagram LinkedIn