CVE-2026-107804: Nginx UI: Bundled reverse proxy can bypass IP allowlists and enable shared login lockout
Nginx UI is a web user interface for the Nginx web server. From 2.2.0 until 2.6.0, the bundled reverse proxy does not preserve the external client identity used by Gin because the backend has no trusted proxy configuration. Management requests can be attributed to loopback and pass the IP allowlist loopback exception, although valid credentials are still required. Failed logins from different external clients are also attributed to the same loopback address, allowing an unauthenticated attacker to trigger a shared temporary login ban for password or OTP authentication without invalidating existing sessions. This issue is fixed in version 2.6.0.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
Nginx UIto a version that resolves this vulnerability.Fixed in 2.6.0
Event History
Frequently Asked Questions
Who is exposed to the IP allowlist bypass?
Deployments using the bundled reverse proxy in affected versions are exposed where management access relies on an IP allowlist and its loopback exception. An attacker still needs valid credentials to access management functions.
What can an unauthenticated attacker do?
They can submit failed password or OTP login attempts that are attributed to the shared loopback address. This can trigger a temporary login ban affecting other external clients, but it does not invalidate existing sessions.
Which versions are affected and what version fixes the issue?
Versions from 2.2.0 until 2.6.0 are affected. The issue is fixed in version 2.6.0.