Description
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.
References5
- github.com/mlogclub/bbs-go/blob/v4.4.6/internal/pkg/google/jwt.…
- github.com/mlogclub/bbs-go/blob/v4.4.6/internal/services/third_…
- hackmd.io/@hieuPenguinnn/bbs-go-google-one-tap-id-token-audienc…
- www.vulncheck.com/advisories/bbs-go-through-4.4.6-account-takeo…
- hackmd.io/@hieuPenguinnn/bbs-go-google-one-tap-id-token-audienc…
Metrics
- CVSS 3.1
-
8.1
HIGH
Score source: CNA
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N - CVSS 4.0
-
8.6
HIGH
Score source: CNA
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - EPSS — exploit probability
- 0% percentile: 41 · as of 10 November 2026
- CWE
- CWE-287
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.