Vulnerability · Published Oct 16, 2026 · Assigned by VulnCheck

CVE-2026-111639bbs-go through 4.4.6 Account Takeover via Google One Tap Login

High 8.1

In plain English

A high-severity improper authentication in bbs-go from mlogclub. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 41% of all known vulnerabilities).

Severity (CVSS 3.1)8.1High

Exploit odds (30 days)0.5%top 59.0% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

Official 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.

Affected products (as reported)

Vendor	Product	Versions
mlogclub	bbs-go	0 – through 4.4.6

Weakness: CWE-287 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N

References

https://hackmd.io/@hieuPenguinnn/bbs-go-google-one-tap-id-token-audience-confusion-account-takeover third-party-advisory
https://github.com/mlogclub/bbs-go/blob/v4.4.6/internal/pkg/google/jwt.go#L55-L58 technical-description
https://github.com/mlogclub/bbs-go/blob/v4.4.6/internal/services/third_user_service.go#L274-L293 technical-description
VulnCheck Advisory: bbs-go through 4.4.6 Account Takeover via Google One Tap Login third-party-advisory