CVE-2026-23478

Cal.com has an Authentication Bypass via Unvalidated Email in Custom JWT Callback

State: Published
Severity: 10.0 Critical
Published: Jan 13, 2026
Updated: Jan 14, 2026
Reserved: Jan 13, 2026

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.

Scores

CVSS	Score	Vector	Source
4.0	10.0 Critical	CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:L	GitHub_M

Weaknesses

CWE-602 Client-Side Enforcement of Server-Side Security
CWE-639 Authorization Bypass Through User-Controlled Key

Affected Products

Product	Versions
cal.comcalcom	>= 3.1.6, < 6.0.7Affected

References

https://github.com/calcom/cal.com/security/advisories/GHSA-7hg4-x4pr-3hrg

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