CVE-2025-66489
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedCal.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.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceCal.com versions prior to 5.9.8 contain a flaw in the login credentials provider where problematic conditional logic in the authentication flow allows password verification to be bypassed when a TOTP code is provided, potentially granting unauthorized access to user accounts.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data< 5.9.8CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Identify installed Cal.com versionLocate the package.json file in the Cal.com installation directory and check the 'version' field, or access the Cal.com admin settings page to view the application versionAffected if The version number is lower than 5.9.8 (e.g., 5.9.7, 5.9.6, etc.)
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Confirm TOTP authentication is availableNavigate to the Cal.com authentication settings or check if the two-factor authentication (2FA/TOTP) feature is enabled in the organization's security settingsAffected if TOTP-based two-factor authentication is enabled or available on the instance
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Verify TOTP is required for loginCheck user account settings or security policies to determine if users have TOTP enforced or have enrolled a TOTP authenticatorAffected if Users have TOTP enabled on their accounts and use it during login with the affected version
The environment is affected if Cal.com version is below 5.9.8 and the login flow involves TOTP code submission, as the conditional logic flaw allows password verification to be bypassed under these conditions.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scoped5.9.8
Upgrade Cal.com to version 5.9.8 or later to remediate the authentication bypass vulnerability.
5.9.8 or later
- 1. Backup your current Cal.com installation and database before upgrading
- 2. Update Cal.com to version 5.9.8 or later using your package manager (e.g., npm install @calcom/[email protected] or pull the latest Docker image)
- 3. Verify the upgrade completed successfully by checking the installed version
- 4. Test the login flow with TOTP-enabled accounts to confirm the authentication bypass is patched
- 5. Review application logs for any suspicious authentication attempts that may have occurred before the patch
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Implementation3.0 h
- Testing4.0 h
- Review / QA3.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,328.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2025-66489 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2025-66489 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
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