---
id: CVE-2026-39912
title: v2board / Xboard Authentication Token Exposure via loginWithMailLink
summary: >-
  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…
severity: critical
cvss: 9.1
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N'
cvssSource: cna
cwe:
  - CWE-201
vendor: v2board
product: v2board
affected:
  - v2board >= 1.6.1 <= 1.7.4
  - >-
    v2board >= bdb10bed32c5f37df2f0872c3cb354e9b7a293bd <=
    0ca47622a50116d0ddd7ffb316b157afb57d25e8
  - Xboard <= 0.1.9
ssvc:
  exploitation: poc
  automatable: 'yes'
  technicalImpact: total
  timestamp: '2026-04-10T20:16:59.517212Z'
exploitAvailable: true
published: '2026-04-09'
updated: '2026-11-08'
sourceUpdated: '2026-11-08T14:02:33.091Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-39912'
references:
  - url: 'https://chocapikk.com/posts/2026/xboard-v2board-account-takeover/'
  - url: 'https://github.com/v2board/v2board/pull/981'
  - url: 'https://github.com/cedar2025/Xboard/pull/873'
  - url: >-
      https://github.com/v2board/v2board/blob/0ca47622a50116d0ddd7ffb316b157afb57d25e8/app/Http/Controllers/Passport/AuthController.php#L71
  - url: >-
      https://github.com/cedar2025/Xboard/blob/1fe6531924cc1ec662a88b9ef725afcf78d660bc/app/Services/Auth/MailLinkService.php#L49
  - url: >-
      https://github.com/cedar2025/Xboard/blob/1fe6531924cc1ec662a88b9ef725afcf78d660bc/app/Http/Controllers/V1/Passport/AuthController.php#L51
  - url: >-
      https://github.com/cedar2025/Xboard/commit/121511523f04882ec0c7447acd9b8ebcb8a47957
  - url: >-
      https://www.vulncheck.com/advisories/v2board-xboard-authentication-token-exposure-via-loginwithmaillink
tags:
  - cve.org
  - exploit-available
epss: 0.00607
epssPercentile: 0.4929
exploits:
  github: 1
  githubRepos:
    - 'https://github.com/Chocapikk/CVE-2026-39912'
  checkedAt: '2026-11-08T14:51:57.347Z'
ingestedAt: '2026-11-08T14:51:22.447Z'
---

## Overview

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

- `v2board >= 1.6.1 <= 1.7.4`
- `v2board >= bdb10bed32c5f37df2f0872c3cb354e9b7a293bd <= 0ca47622a50116d0ddd7ffb316b157afb57d25e8`
- `Xboard <= 0.1.9`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.