# CVE-2026-78863: liketrek TREK MFA bypass in pre-2FA token validation

Source: https://junglewise.ai/threats/cve-2026-78863-liketrek-trek-mfa-bypass-in-pre-2fa-token-validation  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-08-25. Updated: 2026-09-25  
License: CC BY 4.0 with a link back

CVE-2026-78863 · Severity: medium · CVSS 6.3 · Published 2026-08-25

TREK is a travel-planning and expense-sharing application used for organizing group trips. The vulnerability allows attackers who know a user's password to completely bypass multi-factor authentication (MFA) and gain full access to any account by reusing a temporary authentication token that should only be valid for the MFA entry step. This means two-factor authentication offers no protection against credential theft or phishing attacks.

## Quick answers

**Is CVE-2026-78863 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-78863 being exploited in the wild.

**How severe is CVE-2026-78863?** Medium severity, with a CVSS score of 6.3, published 25 August 2026.

**Which products and versions are affected?** liketrek TREK up to 3.0.22.

**Is there a fix for CVE-2026-78863?** A patch was published on 2026-06-16: Fixed in version 3.1.0 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-78863 attacked?** It is attacked over the network.

**Am I affected by CVE-2026-78863?** Check whether anything you run is named in the advisory. 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

The vulnerability is a JWT purpose confusion flaw in the pre-MFA authentication flow. The loginUser function in server/src/services/authService.ts issues a purpose-scoped mfa_token JWT after password verification, but the central session verifier (verifyJwtAndLoadUser in server/src/middleware/auth.ts) never validates the JWT purpose claim—it accepts any token with a matching user ID as a full session token regardless of its intended scope. An attacker with the victim's password calls POST /api/auth/login, receives the mfa_token, and replays it as a Bearer token on authenticated endpoints to bypass the TOTP/backup code check entirely. The flaw affects all users with MFA enabled and default password_version=0. Patch available in version 3.1.0; fix rejects tokens with a purpose claim and binds password_version into the mfa_token for defense-in-depth.

## Affected products

- liketrek TREK up to 3.0.22

## Timeline

- 2026-06: disclosed: Reported via coordinated private disclosure
- 2026-06-16: patched: Fixed in version 3.1.0

## References

- [https://github.com/liketrek/TREK/releases/tag/v3.1.0](https://github.com/liketrek/TREK/releases/tag/v3.1.0)
- [https://github.com/mauriceboe/TREK/security/advisories/GHSA-mjh4-w6fq-54qm](https://github.com/mauriceboe/TREK/security/advisories/GHSA-mjh4-w6fq-54qm)