# CVE-2025-66489: Cal.com Authentication Bypass via bad TOTP + password checks

> Attackers can bypass password verification by providing a TOTP code, gaining unauthorized access to user accounts in Cal.com.

- **Severity:** Critical 9.9 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 3 Dec 2025
- **Updated:** 3 Dec 2025
- **Also known as:** GHSA-9r3w-4j8q-pw98

## What is CVE-2025-66489?

CVE-2025-66489 is a critical authentication bypass vulnerability in calcom cal.com, published on 3 Dec 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official 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.

Weakness: CWE-303 (Incorrect Implementation of Authentication Algorithm)

## Which versions are affected by CVE-2025-66489?

It affects 1 product.


Products: Cal Cal.com.

## How do I fix CVE-2025-66489?

No fix has been published for CVE-2025-66489 yet. Limit exposure of the affected software until one is available.

## Is CVE-2025-66489 being exploited?

There is no known exploitation of CVE-2025-66489 in the wild and no public exploit code.

## Other vulnerabilities in calcom cal.com

- [CVE-2026-23478](https://insights.sbomify.com/CVE-2026-23478/): Cal.com has an Authentication Bypass via Unvalidated Email in Custom JWT Callback (critical 10.0)
- [CVE-2023-1647](https://insights.sbomify.com/CVE-2023-1647/): Improper Access Control in calcom/cal.com (high 8.8)
- [CVE-2023-37919](https://insights.sbomify.com/CVE-2023-37919/): Cal.com not expiring old sessions after enabling 2FA (medium 6.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-66489 and fix it if it is affected.

What it is: CVE-2025-66489 is a critical authentication bypass vulnerability in calcom cal.com, published on 3 Dec 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2025-66489 in the wild and no public exploit code.

Affected product: calcom cal.com. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2025-66489/ (Markdown: https://insights.sbomify.com/CVE-2025-66489/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-66489
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-66489
- OSV: https://osv.dev/vulnerability/CVE-2025-66489

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-66489/
Summaries are generated and may contain mistakes; the official description above is the record.