CVE-2026-111639: bbs-go through 4.4.6 Account Takeover via Google One Tap Login
bbs-go through 4.4.6 contains an authentication bypass vulnerability in the /api/login/googleonetap endpoint that allows remote attackers to log in as other users by submitting Google ID tokens issued to any OAuth client. Attackers operating their own Google OAuth client can capture a victim's Google-signed ID token and replay it, since the aud claim is never checked, to obtain an authenticated session as the victim's Google-linked account.
Affected Software
Event History
Frequently Asked Questions
What does an attacker need to exploit this issue?
The attacker needs a Google-signed ID token for the targeted user that was issued to any OAuth client. An attacker operating their own Google OAuth client can capture such a token and replay it to the affected endpoint.
Which accounts are at risk?
Google-linked accounts are at risk, because a successfully replayed token can create an authenticated session as the victim's linked account. The issue is remotely exploitable and does not require prior privileges on the affected application.
How can I determine whether an installation is affected?
Installations of bbs-go through version 4.4.6 are affected if they expose and use the /api/login/google_one_tap endpoint. The vulnerable behavior is failure to validate the ID token's aud claim, allowing tokens issued for other OAuth clients to be accepted.