CVE-2026-39912
v2board / Xboard Authentication Token Exposure via loginWithMailLink
- State
- Published
- Severity
- 9.1 Critical
- Published
- Apr 9, 2026
- Updated
- Jul 14, 2026
- Reserved
- Apr 7, 2026
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 4.0 | 9.1 Critical | 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 | VulnCheck |
| 3.1 | 9.1 Critical | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N | VulnCheck |
Weaknesses
- CWE-201 Insertion of Sensitive Information Into Sent Data
Affected Products
| Product | Versions |
|---|---|
v2boardv2board |
|
Xboardcedar2025 |
|
References
- https://chocapikk.com/posts/2026/xboard-v2board-account-takeover/technical-descriptionexploit
- https://github.com/v2board/v2board/pull/981issue-tracking
- https://github.com/cedar2025/Xboard/pull/873issue-tracking
- https://github.com/v2board/v2board/blob/0ca47622a50116d0ddd7ffb316b157afb57d25e8/app/Http/Controllers/Passport/AuthController.php#L71related
- https://github.com/cedar2025/Xboard/blob/1fe6531924cc1ec662a88b9ef725afcf78d660bc/app/Services/Auth/MailLinkService.php#L49related
- https://github.com/cedar2025/Xboard/blob/1fe6531924cc1ec662a88b9ef725afcf78d660bc/app/Http/Controllers/V1/Passport/AuthController.php#L51related
- https://github.com/cedar2025/Xboard/commit/121511523f04882ec0c7447acd9b8ebcb8a47957patch
- https://www.vulncheck.com/advisories/v2board-xboard-authentication-token-exposure-via-loginwithmaillinkthird-party-advisory
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