CVE-2026-39912

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.

CVSS v4.0

9.1 CRITICALCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

CVSS v3.1

9.1 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

EPSS

0.58% chance of exploitation in the next 30 days, 46th percentile

Published

2026-04-09

Updated

2026-07-14

Proof-of-concept exploits (2)

• https://chocapikk.com/posts/2026/xboard-v2board-account-takeover/
• Chocapikk/CVE-2026-399122★ · 2026-04-09

References

• CVE Record
• NVD entry

Related

• CVE-2026-39908
• CVE-2026-3992
• CVE-2026-39907
• CVE-2026-39920
• CVE-2026-39906
• CVE-2026-3993