CVE-2026-104084

SmarterMail < Build 9777 Stale JWT Role Claim Privilege Escalation via Refresh Token

HIGH 8.7EPSS 0.3%

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: Smartertools · Smartermail
CVSS v4.0 VULNCHECK: 8.7 HIGHCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS v3.1 VULNCHECK: 8.8 HIGHCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
EPSS: 0.27% chance of exploitation in the next 30 days, 18th percentile
Published: 2026-10-09
Updated: 2026-10-12

Proof-of-concept exploits (2)

https://blog.evan.lat/posts/sm/
eev4n/smartermail0★ · 2026-10-12

CVE-2026-104084

Proof-of-concept exploits (2)

References

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