CVE-2026-73683: laravel socialite Authentication Bypass by Capture-replay

Vulnerability summary

CVE-2026-73683 is a critical (CVSS 9.2) Authentication Bypass by Capture-replay vulnerability in laravel socialite. EPSS estimates a 0.76% chance of exploitation in the next 30 days, higher than 54.5% of scored vulnerabilities.

Timeline

1. 14-08-2026
   PublishedVulnerability first disclosed.
2. 18-08-2026
   Last modifiedVulnerability information updated.

Description

Laravel Socialite's Facebook provider contains an authentication bypass vulnerability that allows unauthenticated attackers to replay captured OIDC id_tokens by exploiting the missing nonce claim validation in the getUserByOIDCToken() function within FacebookProvider.php. Attackers who obtain a valid, unexpired id_token issued for the same Facebook App ID can submit the captured token to the backend userFromToken() endpoint, bypassing authentication controls because signature, aud, and iss checks pass while no session-bound nonce comparison is performed, resulting in unauthorized access to victim accounts.

• CWE-294Authentication Bypass by Capture-replayA capture-replay flaw exists when the design of the product makes it possible for a malicious user to sniff network traffic and bypass authentication by replaying it to the server in question to the same effect as the original message (or with minor changes).