by Kastro
Paper/Archive/CVE-2026-39912

CVE-2026-39912

v2board v2board — v2board / Xboard Authentication Token Exposure via loginWithMailLink

EPSS 0.6%public exploitCVSS 9.1
critical.is priorityof 100
47
CVSS 9.1 (CNA)9.1 / 10 × 3027.3Not in CISA KEV+300.0EPSS percentile 48.5.485 × 209.7Exploit: SSVC poc+1010.0SSVC exploitation: poc+100.0
Description · from the CVE record

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.

Affected

ProductAffectedFixed inSource
v2board1.6.1 – 1.7.4–CNA
v2boardbdb10bed32c5f37df2f0872c3cb354e9b7a293bd – 0ca47622a50116d0ddd7ffb316b157afb57d25e8–CNA
Xboard≤ 0.1.9121511523f04882ec0c7447acd9b8ebcb8a47957CNA

Scores by source

VulnCheck (CNA)9.1CVSS: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 (CNA)9.1CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
CISA ADPSSVCExploitation: poc · Automatable: yes · Technical impact: total

References

exploitchocapikk.com/posts/2026/xboard-v2board-account-takeoverrefgithub.com/v2board/v2board/pull/981refgithub.com/cedar2025/Xboard/pull/873refgithub.com/v2board/v2board/blob/0ca47622a50116d0ddd7ffb316b157afb57d25e8/app/Http/Controllers/Passport/AuthController.php#L71refgithub.com/cedar2025/Xboard/blob/1fe6531924cc1ec662a88b9ef725afcf78d660bc/app/Services/Auth/MailLinkService.php#L49refgithub.com/cedar2025/Xboard/blob/1fe6531924cc1ec662a88b9ef725afcf78d660bc/app/Http/Controllers/V1/Passport/AuthController.php#L51patchgithub.com/cedar2025/Xboard/commit/121511523f04882ec0c7447acd9b8ebcb8a47957writeupvulncheck.com/advisories/v2board-xboard-authentication-token-exposure-via-loginwithmaillink