Instituto Nacional de ciberseguridad. Sección Incibe
Instituto Nacional de Ciberseguridad. Sección INCIBE-CERT

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CVE-2026-23478

Severity CVSS v4.0:
CRITICAL
Type:
Unavailable / Other
Publication date:
13/01/2026
Last modified:
13/01/2026

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.

Impact

Vector 4.0
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 CVSS v4.0 Severity and Metrics:

Base Score: 10.00 CRITICAL
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

Attack Vector (AV): Network
Attack Complexity (AC): Low
Attack Requirements (AT): None
Privileges Required (PR): None
User Interaction (UI): None
Confidentiality (VC): High
Integrity (VI): High
Availability (VA): High
Confidentiality (SC): High
Integrity (SI): High
Availability (SA): Low

Base Score 4.0
10.00
Severity 4.0
CRITICAL

References to Advisories, Solutions, and Tools