Unverified Email Authentication Bypass in Firebase WordPress

The Firebase Authentication WordPress plugin before 1.7.1 does not require the email address in an authentication token to be verified before matching it to a WordPress account and issuing a session, allowing unauthenticated attackers to log in as any user, including administrators.

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-2026-76793 is a critical authentication bypass vulnerability in the Firebase Authentication WordPress plugin that allows attackers to assume any user identity, including administrators, without possessing legitimate credentials. The flaw stems from the plugin's failure to validate that email addresses in authentication tokens have been verified before matching them to WordPress accounts and issuing sessions. This affects any WordPress installation running the vulnerable plugin version before 1.7.1, making it an attractive target for attackers seeking immediate administrative access. The vulnerability is particularly dangerous because it requires no prior account compromise or credential theft—attackers can simply craft authentication tokens with unverified email addresses corresponding to existing WordPress users.

Casky's 283 mapped security skills leverage Claude's extended reasoning to detect the attack patterns underlying this vulnerability across MITRE ATT&CK's Initial Access (TA0004) and Credential Access (TA0006) techniques. Practitioners using Casky would observe findings related to anomalous authentication token validation patterns, specifically detection of authentication attempts where email verification status is bypassed before account matching occurs. The platform would flag suspicious session creation tied to unverified email identities, token generation without proper cryptographic binding to verified email states, and lateral privilege escalation indicators where standard user accounts are suddenly elevated to administrator roles through authentication bypass chains. These skill-driven detections enable security teams to identify exploitation attempts in real-time and distinguish legitimate authentication flows from malicious token-based takeover attempts.

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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-2026-76793.

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-2026-76793

Casky has 283 skills that investigate the attack patterns behind CVE-2026-76793. Run one and get CVSS-scored findings in 3 minutes.

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