bbs-go through 4.4.6 contains an authentication bypass vulnerability in the /api/login/google_one_tap 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.
Attack Parameters
Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Attack Requirements
None
No additional conditions
Privileges Required
None
No privileges needed
User Interaction
Passive
Minimal interaction
Impact Assessment
Confidentiality
High
Complete data leak
Integrity
High
Complete data modification
Availability
None
No disruption
CVSS Vector v4.0
Weakness Type (CWE)
References 4
https://github.com/mlogclub/bbs-go/blob/v4.4.6/internal/pkg/google/jwt.go#L55-L…
disclosure@vulncheck.com
https://github.com/mlogclub/bbs-go/blob/v4.4.6/internal/services/third_user_ser…
disclosure@vulncheck.com
https://hackmd.io/@hieuPenguinnn/bbs-go-google-one-tap-id-token-audience-confus…
disclosure@vulncheck.com
https://www.vulncheck.com/advisories/bbs-go-through-4.4.6-account-takeover-via-…
disclosure@vulncheck.com