CVE-2026-33031: Nginx-UI: Disabled users retain full API access through previously issued bearer tokens
Summary
A user who was disabled by an administrator can use previously issued API tokens for up to the token lifetime. In practice, disabling a compromised account does not actually terminate that user’s access, so an attacker who already stole a JWT can continue reading and modifying protected resources after the account is marked disabled.
Since tokens can be used to create new accounts, it is possible the disabled user to maintain the privilege.
Details
The application exposes an account-level disable control through the users management API. Login process correctly enforces that control: https://github.com/0xJacky/nginx-ui/blob/6ec542fd97abf2c5950f374f78a32938ad0030e6/internal/user/login.go#L29-L31
However, token-based authentication does not enforce the same check (This code validates token structure and expiry, but returns that user object without checking user.Status.): https://github.com/0xJacky/nginx-ui/blob/6ec542fd97abf2c5950f374f78a32938ad0030e6/internal/user/user.go#L44-L139
There’s also no token revocation feature, unlike when a password is changed: https://github.com/0xJacky/nginx-ui/blob/6ec542fd97abf2c5950f374f78a32938ad0030e6/api/user/user.go#L38-L51
As a result, a disabled user can continue to have full API access. In particular, since that includes account creation, they can create a new account and keep operating even after the JWT expires.
PoC
The issue was validated with version 2.3.3 using the uozi/nginx-ui:sha-c92ec0a docker image.
View the PoC video:
https://github.com/user-attachments/assets/7a5175cb-2f79-4c1b-adad-e7d0bf2ea2bd
Impact
Administrators who rely on "disable user" as an authentication or authorization control can be bypassed.
The disabled user can keep reading sensitive configuration and executing authenticated state-changing actions allowed to that account.
Other sources
Nginx UI is a web user interface for the Nginx web server. Prior to version 2.3.4, a user who was disabled by an administrator can use previously issued API tokens for up to the token lifetime. In practice, disabling a compromised account does not actually terminate that user’s access, so an attacker who already stole a JWT can continue reading and modifying protected resources after the account is marked disabled. Since tokens can be used to create new accounts, it is possible the disabled user to maintain the privilege. Version 2.3.4 patches the issue.
— MITRE
Affected Software
Event History
Frequently Asked Questions
What is the severity of CVE-2026-33031?
The severity of CVE-2026-33031 is considered high due to the risk of unauthorized access through disabled user API tokens.
How do I fix CVE-2026-33031?
To fix CVE-2026-33031, upgrade Nginx UI to version 2.3.4 or later to ensure that disabled users cannot access the API.
What systems are affected by CVE-2026-33031?
CVE-2026-33031 affects all versions of Nginx UI prior to 2.3.4.
What are the implications of CVE-2026-33031?
The implications of CVE-2026-33031 include potential unauthorized access to sensitive API operations by disabled users.
Can previously issued API tokens be used after a user is disabled in CVE-2026-33031?
Yes, previously issued API tokens can be used by disabled users until the token's expiration period lapses.