CVE-2026-111639
Received Received - Intake

Authentication Bypass in BBS-Go via Google One Tap

Publication date: 2026-10-16

Last updated on: 2026-10-16

Assigner: VulnCheck

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.

CVSS Scores

EPSS Scores

Probability:
Percentile:

Meta Information

Published
2026-10-16
Last Modified
2026-10-16
Generated
2026-10-16
AI Q&A
2026-10-16
EPSS Evaluated
N/A
NVD
CVE-2026-111639
EUVD
EUVD-2026-103061

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
mlogclub bbs-go 0

Helpful Resources

Exploitability

CWE
CWE Icon
KEV
KEV Icon
CWE ID Description
CWE-287 When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct.

Attack-Flow Graph

AI Quick Actions

Instant insights powered by AI
Executive Summary

CVE-2026-111639 is an authentication bypass vulnerability in bbs-go versions up to 4.4.6. It affects the /api/login/google_one_tap endpoint where the application fails to verify the 'aud' claim in Google ID tokens. Attackers can capture a victim's Google-signed ID token and replay it through their own OAuth client to log in as the victim without proper validation.

Detection Guidance

To detect this vulnerability, inspect network traffic for POST requests to /api/login/google_one_tap with Google ID tokens. Check if the application validates the 'aud' claim in tokens. Review logs for unusual login attempts or account access patterns.

Impact Analysis

This vulnerability allows remote attackers to take over user accounts by exploiting improper token validation. If you use bbs-go with Google One Tap login, an attacker could gain unauthorized access to your account by replaying your Google ID token. This could lead to data theft, account misuse, or further compromise of your system.

Compliance Impact

This vulnerability could lead to unauthorized access to sensitive user data, violating GDPR's data protection principles and HIPAA's security requirements. It may result in non-compliance due to insufficient authentication controls, potentially leading to data breaches and regulatory penalties.

Mitigation Strategies

Immediately update bbs-go to a patched version beyond 4.4.6. Ensure the application validates the 'aud' claim in Google ID tokens against the configured OAuth client ID. Implement local token verification using Google's public keys instead of relying solely on the tokeninfo endpoint.

Chat Assistant

Ask questions about this CVE
Hi! I’m here to help you understand CVE-2026-111639. Ask me anything about the vulnerability, its impact, or mitigation strategies.
0/70

EPSS Chart