Vulnerability in Cedar2025 Xboard
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.
EPSS: 0.006 (44.5th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 9.1 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N.
Affected products
- Cedar2025 Xboard — versions 0, 121511523f04882ec0c7447acd9b8ebcb8a47957
- V2board — versions 1.6.1, bdb10bed32c5f37df2f0872c3cb354e9b7a293bd
Weakness classification (CWE)
Public proof-of-concept exploits
References
- disclosure@vulncheck.com (technical-description, exploit)
- disclosure@vulncheck.com (issue-tracking, mitigation)
- disclosure@vulncheck.com (issue-tracking, mitigation)
- disclosure@vulncheck.com (related)
- disclosure@vulncheck.com (related)
- disclosure@vulncheck.com (related)
- disclosure@vulncheck.com (patch)
- disclosure@vulncheck.com (third-party-advisory)
Frequently asked questions
- What is CVE-2026-39912?
- CVE-2026-39912 is a critical-severity vulnerability in Cedar2025 Xboard, classified under Insertion of Sensitive Information into Sent Data. CVSS score: 9.1/10. Published 2026-04-09.
- How severe is CVE-2026-39912?
- Critical severity. CVSS v3 base score is 9.1 out of 10.
- Is CVE-2026-39912 known to be exploited?
- 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.