What’s Vulnerable › Vulnerabilities

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

• Severity: high (CVSS 8.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-10-16 · updated 2026-10-21
• Weakness: CWE-287

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

• mlogclub bbs-go: through 4.4.6

References

• https://github.com/mlogclub/bbs-go/blob/v4.4.6/internal/pkg/google/jwt.go#L55-L58
• https://github.com/mlogclub/bbs-go/blob/v4.4.6/internal/services/third_user_service.go#L274-L293
• https://hackmd.io/@hieuPenguinnn/bbs-go-google-one-tap-id-token-audience-confusion-account-takeover
• https://www.vulncheck.com/advisories/bbs-go-through-4.4.6-account-takeover-via-google-one-tap-login
• https://hackmd.io/@hieuPenguinnn/bbs-go-google-one-tap-id-token-audience-confusion-account-takeover

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