EUVD-2026-21043
GHSA-83h9-46h8-whf4
CVSS Vector
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/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
Lifecycle Timeline
5Description
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.
Analysis
Authentication bypass in V2Board 1.6.1-1.7.4 and Xboard ≤0.1.9 enables unauthenticated account takeover including admin privileges. When login_with_mail_link_enable is active, attackers POST known email addresses to the loginWithMailLink endpoint, receiving full authentication URLs in HTTP responses. …
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Remediation
Within 24 hours: Identify all V2Board and Xboard instances in production and verify affected versions. Within 7 days: Apply vendor-released patch to V2Board ≥1.7.5 and Xboard ≥0.2.0, or immediately disable the login_with_mail_link_enable feature if patching cannot be completed. …
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External POC / Exploit Code
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