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.
https://github.com/calcom/cal.com/security/advisories/GHSA-7hg4-x4pr-3hrg
Published: 2026-01-13
Updated: 2026-01-14
Base Score: 5.5
Vector: CVSS2#AV:N/AC:L/Au:S/C:P/I:P/A:N
Severity: Medium
Base Score: 8.8
Vector: CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Severity: High
Base Score: 10
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
Severity: Critical
EPSS: 0.00072