Description
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.
CVSS breakdown
CVSS 4.0
Attack Vector
Network
Attack Complexity
Low
Attack Requirements
Present
Privileges Required
None
User Interaction
None
Confidentiality (Vulnerable System)
High
Integrity (Vulnerable System)
High
Availability (Vulnerable System)
None
Confidentiality (Subsequent System)
None
Integrity (Subsequent System)
None
Availability (Subsequent System)
None
CVSS 3.1
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
None
Affected products
- cedar2025 / Xboard0 – 0.1.9
- cedar2025 / Xboard121511523f04882ec0c7447acd9b8ebcb8a47957 – 121511523f04882ec0c7447acd9b8ebcb8a47957
- v2board / v2board1.6.1 – 1.7.4
- v2board / v2boardbdb10bed32c5f37df2f0872c3cb354e9b7a293bd – 0ca47622a50116d0ddd7ffb316b157afb57d25e8
References
- MISChttps://chocapikk.com/posts/2026/xboard-v2board-account-takeover/
- PATCHhttps://github.com/v2board/v2board/pull/981
- PATCHhttps://github.com/cedar2025/Xboard/pull/873
- MISChttps://github.com/v2board/v2board/blob/0ca47622a50116d0ddd7ffb316b157afb57d25e8/app/Http/Controllers/Passport/AuthController.php#L71
- MISChttps://github.com/cedar2025/Xboard/blob/1fe6531924cc1ec662a88b9ef725afcf78d660bc/app/Services/Auth/MailLinkService.php#L49
- MISChttps://github.com/cedar2025/Xboard/blob/1fe6531924cc1ec662a88b9ef725afcf78d660bc/app/Http/Controllers/V1/Passport/AuthController.php#L51
- PATCHhttps://github.com/cedar2025/Xboard/commit/121511523f04882ec0c7447acd9b8ebcb8a47957
- VENDOR_ADVISORYhttps://www.vulncheck.com/advisories/v2board-xboard-authentication-token-exposure-via-loginwithmaillink