CVE-2026-39912 CRITICAL

CVE-2026-39912: v2board / Xboard Authentication Token Exposure via loginWithMailLink

Vendor V2Board
Product v2board
Weakness CWE-201
Published April 9, 2026
Last update May 25, 2026

CVSS base score

9.1/10
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Confidentiality
Integrity

CVSS vector

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

What the vulnerability does

01Description

V2Board 1.6.1 through 1.7.4 and Xboard through 0.1.9 expose authentication tokens in HTTP response bodies of the loginWithMailLink endpoint when the login_with_mail_link_enable feature is active. Unauthenticated attackers can POST to the loginWithMailLink endpoint with a known email address to receive the full authentication URL in the response, then exchange the token at the token2Login endpoint to obtain a valid bearer token with complete account access including admin privileges.

Key dates

02Disclosure timeline

April 9, 2026 CVE published
May 25, 2026 Record updated