CVE-2026-39912
v2board / Xboard Authentication Token Exposure via loginWithMailLink
CVSS Score
9.1
EPSS Score
0.1%
EPSS Percentile
19th
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.
| CWE | CWE-201 |
| Vendor | v2board |
| Product | v2board |
| Published | Apr 9, 2026 |
| Last Updated | Apr 13, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
None
Affected Versions
v2board / v2board
1.6.1 ≤ 1.7.4 bdb10bed32c5f37df2f0872c3cb354e9b7a293bd ≤ 0ca47622a50116d0ddd7ffb316b157afb57d25e8
cedar2025 / Xboard
0 ≤ 0.1.9
References
chocapikk.com: https://chocapikk.com/posts/2026/xboard-v2board-account-takeover/ github.com: https://github.com/v2board/v2board/pull/981 github.com: https://github.com/cedar2025/Xboard/pull/873 github.com: https://github.com/v2board/v2board/blob/0ca47622a50116d0ddd7ffb316b157afb57d25e8/app/Http/Controllers/Passport/AuthController.php#L71 github.com: https://github.com/cedar2025/Xboard/blob/1fe6531924cc1ec662a88b9ef725afcf78d660bc/app/Services/Auth/MailLinkService.php#L49 github.com: https://github.com/cedar2025/Xboard/blob/1fe6531924cc1ec662a88b9ef725afcf78d660bc/app/Http/Controllers/V1/Passport/AuthController.php#L51 github.com: https://github.com/cedar2025/Xboard/commit/121511523f04882ec0c7447acd9b8ebcb8a47957 vulncheck.com: https://www.vulncheck.com/advisories/v2board-xboard-authentication-token-exposure-via-loginwithmaillink
Credits
Valentin Lobstein (Chocapikk)