CVE-2026-23478 CRITICAL

CVE-2026-23478: Cal.com has an Authentication Bypass via Unvalidated Email in Custom JWT Callback

Vendor Calcom
Product cal.com
Weakness CWE-602 · Client-side enforcement
Published January 13, 2026
Last update January 14, 2026
View on NVD All CVEs

CVSS base score

10.0/10
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Confidentiality —
Integrity —

CVSS vector

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

What the vulnerability does

01Description

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.

Key dates

02Disclosure timeline

January 13, 2026 CVE published
January 14, 2026 Record updated