Cal.com has an Authentication Bypass via Unvalidated Email in Custom JWT Callback
Priority MEDIUM 49CWE-602Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Attack requirements
- None
- Impact type
- Security bypass
- Confidentiality · integrity · availability
- High · High · High
- Fix status
- Fixed
Attack profile from CVSS 4.0 · CNA. Fix status from CNA. Impact type from CWE-639.
Summary
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.
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00466 40th percentileScored 2026-11-07
Fix Fixed cal.com (calcom): 6.0.7
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- Yes
- Technical impact
- Total
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
Remediation
- Fix · CNA cal.com (calcom) Fixed in 6.0.7
Timeline
- 2026-10-02 Threatist record created from CVE-2026-23478
References
More calcom Cal.com vulnerabilities
- TI-2023-19352 Cal.com not expiring old sessions after enabling 2FA CVSS 3.1MEDIUM 6.5
- TI-2025-40913 Cal.com Authentication Bypass via bad TOTP + password checks CVSS 4.0CRITICAL 9.9
- TI-2023-01550 Improper Access Control in calcom/cal.com CVSS 3.1HIGH 8.8
Sources
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences