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TI-2025-40913 Aliases CVE-2025-66489

Cal.com Authentication Bypass via bad TOTP + password checks

Priority MEDIUM 44CWE-303Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Attack requirements
None
Impact type
—
Confidentiality · integrity · availability
High · High · High
Fix status
Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA.

Summary

Cal.com is open-source scheduling software. Prior to 5.9.8, A flaw in the login credentials provider allows an attacker to bypass password verification when a TOTP code is provided, potentially gaining unauthorized access to user accounts. This issue exists due to problematic conditional logic in the authentication flow. This vulnerability is fixed in 5.9.8.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00967 61st percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix Fixed cal.com (calcom): 5.9.8

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
No
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
calcomcal.combefore 5.9.85.9.8Patch availableCNA
  • cal.com Vendorcalcom Affected before 5.9.8 Fixed in 5.9.8 Patch available CNA

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:cal:cal.com:*:*:*:*:*:*:*:*before 5.9.8Vulnerablecalcom
  • cpe:2.3:a:cal:cal.com:*:*:*:*:*:*:*:* Versions before 5.9.8 Vulnerable ·calcom

Remediation

  • Fix · CNA cal.com (calcom) Fixed in 5.9.8

Timeline

  1. 2026-10-02 Threatist record created from CVE-2025-66489

References

Exploit 1

  • TI-2023-19352 Cal.com not expiring old sessions after enabling 2FA CVSS 3.1MEDIUM 6.5
  • TI-2026-18911 Cal.com has an Authentication Bypass via Unvalidated Email in Custom JWT Callback CVSS 4.0CRITICAL 10.0
  • 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