OTP step-up bypass in Nginx UI MCP configuration tools
Key facts
- Attack vector
- Network
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Security bypass
- Confidentiality · integrity · availability
- None · High · High
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-288.
Summary
Nginx UI, a web user interface for the Nginx web server, is affected before 2.4.1. The HTTP configuration change routes require a secure session check, but the /mcp and /mcp_message routes only require ordinary authentication before exposing the nginx_config_add and nginx_config_modify tools (CWE-288). An OTP-enabled user with a normal JWT but no valid secure session can create or modify Nginx configuration and trigger reloads through MCP, bypassing the intended step-up control.
Written with Claude Haiku 5.5 from the sources below · 2026-10-29
Description from the CNA
Nginx UI is a web user interface for the Nginx web server. Prior to 2.4.1, the HTTP configuration mutation routes require RequireSecureSession, but /mcp and /mcp_message require only ordinary authentication before exposing nginx_config_add and nginx_config_modify. An OTP-enabled user with a normal JWT but no valid X-Secure-Session-ID can therefore create or modify Nginx configuration and trigger reload behavior through MCP, bypassing the intended step-up control. This issue is fixed in version 2.4.1.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- Poc
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| 0xJacky | nginx-ui | before 2.4.1 | 2.4.1 | Patch available | CNA |
| — | github.com/0xJacky/Nginx-UI (Go) | before 1.9.10-0.20260703131214-23d1934099b0 | 1.9.10-0.20260703131214-23d1934099b0 | Patch available | GHSA-vc32-4gwf-77xp |
- nginx-ui Vendor0xJacky Affected before 2.4.1 Fixed in 2.4.1 Patch available CNA
- github.com/0xJacky/Nginx-UI (Go) Vendor— Affected before 1.9.10-0.20260703131214-23d1934099b0 Fixed in 1.9.10-0.20260703131214-23d1934099b0 Patch available GHSA-vc32-4gwf-77xp
Remediation
Update Nginx UI to version 2.4.1 or later. For the Go module github.com/0xJacky/Nginx-UI, update to 1.9.10-0.20260703131214-23d1934099b0 or later. The sources do not list a vendor advisory identifier for this fix.
Written with Claude Haiku 5.5 from the sources below · 2026-10-29
- Fix · CNA nginx-ui (0xJacky) Fixed in 2.4.1
- Fix · GHSA-vc32-4gwf-77xp github.com/0xJacky/Nginx-UI (Go) Fixed in 1.9.10-0.20260703131214-23d1934099b0 Advisory →
Timeline
- 2026-10-12 Threatist record created from CVE-2026-84360
- 2026-10-13 CISA SSVC decision points changed
- 2026-10-13 Priority changed: MEDIUM → HIGH
- 2026-10-16 Alias added: GHSA-vc32-4gwf-77xp
- 2026-10-16 Fix available: Go/github.com/0xJacky/[email protected] · GHSA-vc32-4gwf-77xp
- 2026-10-16 CVSS score added · GHSA-vc32-4gwf-77xp
- 2026-10-16 Weakness changed · GHSA-vc32-4gwf-77xp
- 2026-10-16 5 new references · GHSA-vc32-4gwf-77xp
References
More 0xJacky vulnerabilities
- TI-2026-25478 Nginx UI: Unauthenticated MCP Endpoint Allows Remote Nginx Takeover CVSS 3.1CRITICAL 9.8
- TI-2026-25472 nginx-ui Backup Restore Allows Tampering with Encrypted Backups CVSS 4.0CRITICAL 9.4
- TI-2026-22288 Nginx UI: Unauthenticated Backup Download with Encryption Key Disclosure CVSS 3.1CRITICAL 9.8
- TI-2024-15821 Nginx-UI arbitrary file write through the Import Certificate feature CVSS 3.1CRITICAL 9.8
- TI-2026-70057 Code injection in Nginx UI backup restore allows code execution CVSS 4.0CRITICAL 9.4
- TI-2026-32056 Nginx UI: Server-Side Request Forgery (SSRF) via Cluster Proxy Middleware Allows Access to Internal Services CVSS 3.1CRITICAL 9.9
Sources
- CVE-2026-84360 · CVE Program
- CVE-2026-84360 · NVD
- FIRST EPSS
- GHSA-vc32-4gwf-77xp · GitHub Advisory Database · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences