# CVE-2026-36727: BookCars authentication bypass via forged JWT in social-sign-in

Source: https://junglewise.ai/threats/cve-2026-36727-bookcars-authentication-bypass-via-forged-jwt-in-social-sign-in  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-06-09. Updated: 2026-06-09  
License: CC BY 4.0 with a link back

CVE-2026-36727 · Severity: info · CVSS 9.8 · Published 2026-06-09

BookCars, a car rental management system, contains a security flaw in how it handles social media logins (such as Facebook or Apple). An attacker can bypass the login process by creating a fake digital identity token, allowing them to gain full access to any user's account. This could lead to the theft of customer personal information, unauthorized bookings, and complete control over administrative or user accounts.

Technologies: [BookCars](https://junglewise.ai/threats/technologies/bookcars). Vendors: [BookCars](https://junglewise.ai/threats/vendors/bookcars).

## Quick answers

**Is CVE-2026-36727 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-36727 being exploited in the wild.

**How severe is CVE-2026-36727?** Informational severity, with a CVSS score of 9.8, published 9 June 2026.

**Which products and versions are affected?** BookCars <= v8.3.

**Is there a fix for CVE-2026-36727?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-36727 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2026-36727?** Check whether you run BookCars at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

An authentication bypass vulnerability exists in the `/api/social-sign-in` endpoint of BookCars (up to and including v8.3). The application fails to properly validate the signature of JSON Web Tokens (JWT) provided during social sign-in flows (e.g., Facebook, Apple). Instead of verifying the token against the provider's public keys, the system accepts base64-encoded JSON payloads without cryptographic verification. A remote, unauthenticated attacker can exploit this by crafting a forged JWT to impersonate any user, leading to full account takeover. Affected files include `userRoutes.ts`, `userController.ts`, and `authHelper.ts`.

## Affected products

- BookCars BookCars <= v8.3

## Timeline

- 2026-06-09: disclosed
- 2026-06-09: advisory

## References

- [https://github.com/CC-T-454455/Vulnerabilities/tree/master/bookcars/vulnerability-1](https://github.com/CC-T-454455/Vulnerabilities/tree/master/bookcars/vulnerability-1)

## Related threats

- [BookCars arbitrary file deletion via directory traversal in delete-temp-license](https://junglewise.ai/threats/cve-2026-36726-bookcars-arbitrary-file-deletion-via-directory-traversal-in)
- [BookCars unrestricted file rename in /api/create-user component](https://junglewise.ai/threats/cve-2026-36723-bookcars-unrestricted-file-rename-in-api-create-user-component)
- [BookCars arbitrary file upload in create-license and create-car-image API](https://junglewise.ai/threats/cve-2026-36722-bookcars-arbitrary-file-upload-in-create-license-and-create-car)
- [bookcars authentication bypass via forged JWT in validateAccessToken](https://junglewise.ai/threats/cve-2026-36721-bookcars-authentication-bypass-via-forged-jwt-in)
- [BookCars privilege escalation in update-user endpoint](https://junglewise.ai/threats/cve-2026-36720-bookcars-privilege-escalation-in-update-user-endpoint)