MStore API WordPress Plugin Token Signature Verification Bypass

The MStore API WordPress plugin before 4.21.0 does not correctly verify the cryptographic signature of the token used to authenticate its phone-based login, allowing unauthenticated attackers who know a registered user's phone number to forge a token and take over that user's account, including administrator accounts.

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

CVE-2026-16030 exploits a critical cryptographic weakness in the MStore API WordPress plugin's phone-based login mechanism. The plugin fails to properly verify the digital signature of authentication tokens, enabling attackers who possess only a registered user's phone number to forge valid tokens and gain complete account access—including administrator privileges. This vulnerability affects any WordPress installation running the vulnerable plugin version, creating a severe authentication bypass that requires no prior compromise or complex exploitation techniques. The attack surface is particularly dangerous because phone numbers are often considered semi-public information, dramatically lowering the barrier to exploitation.

Casky's 283 matched security skills leverage Claude's extended reasoning to detect the attack chain associated with TA0004 (Initial Access) and TA0006 (Credential Access). Practitioners using Casky would identify suspicious patterns including: token generation requests from unusual geographic origins, multiple authentication attempts using valid phone numbers within short timeframes, and successful logins immediately following failed authentication attempts—all indicators of token forgery. The platform's skills would flag CWE-287 (Improper Authentication) violations through behavioral analysis of cryptographic validation failures and unusual session establishment patterns. A practitioner's dashboard would surface anomalous login sequences where the same phone number generates multiple valid sessions across different devices or IP addresses, combined with administrative action logs that correlate with these forged token events, enabling rapid detection of active exploitation before lateral movement or privilege escalation occurs.

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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 →

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-2026-16030.

abusing-dpapi-for-credential-access

red teaming · high

Run

abusing-shadow-credentials-for-privesc

red teaming · high

Run

Access with Stolen Session Cookie

cryptography · low

Run

MITRE ATT&CK Techniques

TA0004 TA0006

Investigate the attack patterns behind CVE-2026-16030

Casky has 283 skills that investigate the attack patterns behind CVE-2026-16030. Run one and get CVSS-scored findings in 3 minutes.

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