CVE-2026-13447
MStore API <= 4.20.0 - Unauthenticated Authentication Bypass via 'id_token' Parameter JWT Forgery
- Published
- Sep 5, 2026
- Updated
- Sep 7, 2026
- Assigning CNA
- Wordfence
- Evidence observed
- Sep 19, 2026
Primary CVSS
nvd · CVSS 3.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HLow · next 30 days
- Percentile
- 31.8%
- Model date
- Sep 21, 2026
EPSS is a statistical estimate, not a certainty or a measure of impact. Combine it with CVSS, KEV status, exposure and your environment.
Summary
The Mstore Api plugin for WordPress is vulnerable to Authentication Bypass via JWT Forgery in versions up to, and including, 4.20.0 This is due to missing cryptographic signature verification in the FirebasePhoneAuthHelper::verify_id_token() function, which decodes and validates Firebase ID token claims (alg, kid, aud, iss) but never calls openssl_verify() or any equivalent to validate the JWT signature against Google's actual public key certificates. This makes it possible for unauthenticated attackers to forge a Firebase Phone Auth JWT signed with a self-generated RSA key pair and impersonate any phone number, resulting in unauthorized access to existing WordPress accounts or creation of new arbitrary accounts.
Sources
1Proof-of-concept exploit for CVE-2026-13447, a critical authentication bypass in the WordPress MStore API plugin via forged Firebase JWT tokens, with a local lab reproduction.
Responsible use
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