CVE-2026-39912 v2board / Xboard Authentication Token Exposure via loginWithMailLink
Attackers can obtain authentication tokens via the loginWithMailLink endpoint to gain full account access, including admin privileges, when mail link login is enabled.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-39912?
CVE-2026-39912 is a critical vulnerability in cedar2025 Xboard, published on 9 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Weakness: CWE-201
Which versions are affected by CVE-2026-39912?
How do I fix CVE-2026-39912?
No fix has been published for CVE-2026-39912 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-39912 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-39912 exists.
Public exploit code: 1 proofs of concept on GitHub.
Sources
Also known as GHSA-83h9-46h8-whf4.