---
id: CVE-2026-111639
title: bbs-go through 4.4.6 Account Takeover via Google One Tap Login
summary: >-
  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 ope…
severity: high
cvss: 8.1
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N'
cvssSource: cna
cwe:
  - CWE-287
vendor: mlogclub
product: bbs-go
affected:
  - bbs-go <= 4.4.6
published: '2026-10-16'
updated: '2026-10-16'
sourceUpdated: '2026-10-16T17:39:10.284Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-111639'
references:
  - url: >-
      https://hackmd.io/@hieuPenguinnn/bbs-go-google-one-tap-id-token-audience-confusion-account-takeover
  - url: >-
      https://github.com/mlogclub/bbs-go/blob/v4.4.6/internal/pkg/google/jwt.go#L55-L58
  - url: >-
      https://github.com/mlogclub/bbs-go/blob/v4.4.6/internal/services/third_user_service.go#L274-L293
  - url: >-
      https://www.vulncheck.com/advisories/bbs-go-through-4.4.6-account-takeover-via-google-one-tap-login
    label: >-
      VulnCheck Advisory: bbs-go through 4.4.6 Account Takeover via Google One
      Tap Login
tags:
  - cve.org
ingestedAt: '2026-10-16T18:43:08.682Z'
---

## Overview

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

- `bbs-go <= 4.4.6`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.