Description
SmarterMail before build 9777 contains a privilege escalation vulnerability where JWT access and refresh tokens embed a role claim at issuance that is not revalidated against the account's current role when redeemed through POST /api/v1/auth/refresh-token. Attackers who capture a refresh token issued before an administrator demotion, or a demoted user whose session was not actively polling at the time of demotion, can replay the stale token to obtain a new access token retaining the higher-privilege role (such as DomainAdmin or SysAdmin) until natural token expiry.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Smartertools | Smartermail | < Build 9777 | Build 9777 |
Advisories 1
- WID-SEC-2026-3869 SmarterTools SmarterMail: Mehrere Schwachstellen BSI CERT-Bund (WID) · Oct 11, 2026
References
- Release Notes release-notes patch
- Researcher Blog technical-description exploit
- VulnCheck Advisory: SmarterMail < Build 9777 Stale JWT Role Claim Privilege Escalation via Refresh Token third-party-advisory