# CVE-2026-39912

## Summary

- **CVE ID:** CVE-2026-39912
- **Severity:** CRITICAL
- **CVSS Score:** 9.1 (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)
- **CWE:** CWE-201
- **Published:** Apr 9, 2026
- **Last Modified:** Jul 14, 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.

## Affected Products

- v2board — v2board (1.6.1)
- v2board — v2board (bdb10bed32c5f37df2f0872c3cb354e9b7a293bd)
- cedar2025 — Xboard (0)
- cedar2025 — Xboard (121511523f04882ec0c7447acd9b8ebcb8a47957)

## References

- [CNA](https://chocapikk.com/posts/2026/xboard-v2board-account-takeover/)
- [CNA](https://github.com/v2board/v2board/pull/981)
- [CNA](https://github.com/cedar2025/Xboard/pull/873)
- [CNA](https://github.com/v2board/v2board/blob/0ca47622a50116d0ddd7ffb316b157afb57d25e8/app/Http/Controllers/Passport/AuthController.php#L71)
- [CNA](https://github.com/cedar2025/Xboard/blob/1fe6531924cc1ec662a88b9ef725afcf78d660bc/app/Services/Auth/MailLinkService.php#L49)
- [CNA](https://github.com/cedar2025/Xboard/blob/1fe6531924cc1ec662a88b9ef725afcf78d660bc/app/Http/Controllers/V1/Passport/AuthController.php#L51)
- [CNA](https://github.com/cedar2025/Xboard/commit/121511523f04882ec0c7447acd9b8ebcb8a47957)
- [CNA](https://www.vulncheck.com/advisories/v2board-xboard-authentication-token-exposure-via-loginwithmaillink)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.58%
- **EPSS Percentile:** 46.0

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-11._