# CVE-2026-104084: SmarterMail JWT privilege escalation via stale refresh tokens

Source: https://junglewise.ai/threats/cve-2026-104084-smartermail-before-build-9777-contains-a-privilege-escalation  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-09. Updated: 2026-10-16  
License: CC BY 4.0 with a link back

CVE-2026-104084 · Severity: high · CVSS 8.8 · Published 2026-10-09

SmarterMail is a widely-used email and groupware system serving enterprise customers. A privilege escalation vulnerability allows attackers who obtain a refresh token from before an administrator's demotion to retain high-privileged access (System or Domain Administrator) indefinitely by replaying the token, potentially enabling mail access, user impersonation, and system-wide changes.

Technologies: [SmarterTools SmarterMail](https://junglewise.ai/threats/technologies/smartermail). Vendors: [SmarterTools](https://junglewise.ai/threats/vendors/smartertools).

## Quick answers

**Is CVE-2026-104084 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-104084 being exploited in the wild.

**How severe is CVE-2026-104084?** High severity, with a CVSS score of 8.8, published 9 October 2026.

**Which products and versions are affected?** SmarterTools SmarterMail before build 9777.

**Is there a fix for CVE-2026-104084?** Yes: fixed in SmarterMail build 9777. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-104084 attacked?** It is attacked over the network, in a hosted service.

**Am I affected by CVE-2026-104084?** Check whether you run SmarterTools SmarterMail 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.

## How to fix

- Fixed in SmarterMail build 9777

## Technical details

The vulnerability exists in the JWT token refresh mechanism at POST /api/v1/auth/refresh-token, where role claims embedded in JWT tokens at issuance are never revalidated against the account's current role when the token is redeemed. An attacker who captures a refresh token issued before an administrator was demoted can replay it to obtain a new access token that retains the original higher privilege level until natural token expiry. This affects authentication and authorization enforcement for administrative accounts.

## Affected products

- SmarterTools SmarterMail before build 9777

## Timeline

- 2026-10-09: disclosed
- 2026-10-08: patched: Build 9777 released

## References

- [https://blog.evan.lat/posts/sm/](https://blog.evan.lat/posts/sm/)
- [https://www.smartertools.com/smartermail/release-notes/current](https://www.smartertools.com/smartermail/release-notes/current)

## Related threats

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- [SmarterMail remote code execution with SysAdmin token](https://junglewise.ai/threats/cve-2026-104082-smartermail-before-build-9777-contains-a-remote-code-execution)
- [SmarterTools SmarterMail local file inclusion in reporting API](https://junglewise.ai/threats/cve-2026-7807-smartertools-smartermail-local-file-inclusion-in-reporting-api)
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- [SmarterTools SmarterMail auth bypass in ConnectToHub API](https://junglewise.ai/threats/cve-2026-24423-smartertools-smartermail-auth-bypass-in-connecttohub-api)