CVE-2026-23478 Cal.com has an Authentication Bypass via Unvalidated Email in Custom JWT Callback
Attackers can bypass authentication and take over any user account by exploiting an unvalidated email parameter in the custom JWT callback.
- 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-2026-23478?
CVE-2026-23478 is a critical authentication bypass vulnerability in calcom cal.com, published on 13 Jan 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Cal.com is open-source scheduling software. From 3.1.6 to before 6.0.7, there is a vulnerability in a custom NextAuth JWT callback that allows attackers to gain full authenticated access to any user's account by supplying a target email address via session.update(). This vulnerability is fixed in 6.0.7.
Which versions are affected by CVE-2026-23478?
It affects 1 product.
Products include Cal Cal.com.
How do I fix CVE-2026-23478?
No fix has been published for CVE-2026-23478 yet. Limit exposure of the affected software until one is available.
Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.
Is CVE-2026-23478 being exploited?
There is no known exploitation of CVE-2026-23478 in the wild and no public exploit code.
Other vulnerabilities in calcom cal.com
Sources
Also known as GHSA-7hg4-x4pr-3hrg.