Vulnerability · Published Oct 9, 2026 · Assigned by VulnCheck
CVE-2026-104084SmarterMail < Build 9777 Stale JWT Role Claim Privilege Escalation via Refresh Token
High 8.8
In plain English
A high-severity security flaw in Smartermail from Smartertools. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 24% of all known vulnerabilities).
Official 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 (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Smartertools | Smartermail | 0 – before Build 9777 |
Weakness: CWE-613 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
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