CVE-2025-66489
Cal.com Authentication Bypass via bad TOTP + password checks
Description
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.
INFO
Published Date :
Dec. 3, 2025, 8:16 p.m.
Last Modified :
Dec. 4, 2025, 5:15 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 4.0 | CRITICAL | [email protected] |
Solution
- Upgrade Cal.com to version 5.9.8.
- Verify authentication logic and TOTP implementation.
- Monitor for unauthorized access attempts.
Public PoC/Exploit Available at Github
CVE-2025-66489 has a 1 public
PoC/Exploit available at Github.
Go to the Public Exploits tab to see the list.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2025-66489.
| URL | Resource |
|---|---|
| https://github.com/calcom/cal.com/security/advisories/GHSA-9r3w-4j8q-pw98 |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2025-66489 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2025-66489
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
CVE-2025-66489
Python
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2025-66489 vulnerability anywhere in the article.
-
CybersecurityNews
Critical Cal.com Vulnerability Let Attackers Bypass Authentication Via Fake TOTP Codes
A severe authentication bypass vulnerability has been discovered in cal.com, the popular open-source scheduling platform. Allowing attackers to gain unauthorized access to user accounts by submitting ... Read more
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Daily CyberSecurity
High-Severity lz4-java Flaw (CVE-2025-66566) Leaks Uninitialized Memory During Decompression
A high-severity vulnerability has been unearthed in lz4-java, a widely used Java library for the LZ4 compression algorithm. Tracked as CVE-2025-66566, the flaw carries a CVSS score of 8.2, signaling a ... Read more
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Daily CyberSecurity
Critical Cal.com Flaw (CVE-2025-66489, CVSS 9.9) Allows Authentication Bypass by Submitting Fake TOTP Codes
A severe security vulnerability has been uncovered in Cal.com, the popular open-source scheduling platform positioned as the successor to Calendly. The flaw, which carries a near-maximum severity rati ... Read more
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Daily CyberSecurity
High-Severity WatchGuard Flaws Risk VPN DoS and RCE via IKEv2 Memory Corruption
WatchGuard Technologies has released a critical series of security advisories addressing five high-severity vulnerabilities across its Firebox product line. The flaws, which affect the Fireware OS, co ... Read more
The following table lists the changes that have been made to the
CVE-2025-66489 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
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New CVE Received by [email protected]
Dec. 03, 2025
Action Type Old Value New Value Added Description 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. Added CVSS V4.0 AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X Added CWE CWE-303 Added Reference https://github.com/calcom/cal.com/security/advisories/GHSA-9r3w-4j8q-pw98