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Nginx UI: Bundled reverse proxy can bypass IP allowlists and enable shared login lockout

Moderate severity GitHub Reviewed Published Sep 29, 2026 in 0xJacky/nginx-ui • Updated Oct 9, 2026

Package

gomod github.com/0xJacky/Nginx-UI (Go)

Affected versions

>= 1.9.10-0.20251005005631-6de168c9454, < 1.9.10-0.20260904075558-e30e331303fc

Patched versions

1.9.10-0.20260904075558-e30e331303fc

Description

Summary

In Nginx UI versions 2.2.0 through 2.5.x, the official bundled reverse-proxy topology did not preserve the external client identity used by Gin. The backend treated the local proxy peer as the client because no trusted proxy was configured, while the proxy supplied the actual address in forwarding headers.

Impact

This has two distinct effects in bundled-proxy deployments:

  • IP allowlist enforcement: management API requests forwarded by the bundled proxy were identified as loopback and could pass the loopback exception even when the external source was not in the configured allowlist. Protected management operations still required valid credentials; this did not grant unauthenticated administrator access.
  • Login availability: failed login attempts from different external sources were attributed to one loopback address. An unauthenticated attacker could therefore trigger the shared temporary login-ban threshold and deny password or OTP login to other users behind the proxy until the ban expired. Existing authenticated sessions were not invalidated.

Remediation

Upgrade to Nginx UI 2.6.0 or later. The fix explicitly trusts only the intended bundled proxy, validates configured trusted proxies, uses the resolved client address consistently, and fails closed when an IP allowlist is enabled but the client address is invalid.

Fix commit: 0xJacky/nginx-ui@e30e331

References

@0xJacky 0xJacky published to 0xJacky/nginx-ui Sep 29, 2026
Published by the National Vulnerability Database Oct 9, 2026
Published to the GitHub Advisory Database Oct 9, 2026
Reviewed Oct 9, 2026
Last updated Oct 9, 2026

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
Low

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(12th percentile)

Weaknesses

Origin Validation Error

The product does not properly verify that the source of data or communication is valid. Learn more on MITRE.

CVE ID

CVE-2026-107804

GHSA ID

GHSA-9h23-53f4-q947

Source code

Credits

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