Critical severity · published Jan 13, 2026
CVE-2026-23478
Cal.com has an Authentication Bypass via Unvalidated Email in Custom JWT Callback
9.8
CVSS
0.5%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.5% · higher than 41% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
CA
cal.com · calcom
>= 3.1.6, < 6.0.7 · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-23478
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-23478
Third Party Advisory
https://github.com/calcom/cal.com/security/advisories/GHSA-7hg4-x4pr-3hrg
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