Files
next-ai-draw-io/lib/ssrf-protection.ts
Dayuan Jiang 7b6eb39fa5 fix(parse-url): block SSRF via private/internal URLs (#845)
/api/parse-url accepted any URL the user submitted, fetched it via
@extractus/article-extractor, and returned the body as Markdown. With
ALLOW_PRIVATE_URLS unset (the default after #600) the SSRF guard
short-circuited entirely, so an unauthenticated POST could probe
container ports, read AWS IMDS / GCP metadata, and reach same-VPC
internal services.

- parse-url now always rejects private URLs regardless of
  ALLOW_PRIVATE_URLS. The flag's only legitimate use case is local
  LLM provider baseUrl overrides (validate-model, chat); article
  extraction has no business fetching internal hosts. Local LLM
  setups (Ollama, LM Studio, etc.) are unaffected.
- Strip a trailing dot from the hostname before equality checks so
  the FQDN form "localhost." (which still resolves to 127.0.0.1) is
  caught by the existing string match.

Known follow-ups (not addressed here):
- DNS rebinding: hostnames are matched as strings; a public domain
  resolving to 127.0.0.1 (e.g. localtest.me) is not caught.
- HTTP redirects: @extractus/article-extractor uses cross-fetch with
  default redirect: "follow" and exposes no hook, so a public URL
  302-ing to an internal host still leaks.
2026-05-21 23:54:23 +09:00

66 lines
2.0 KiB
TypeScript

/**
* SSRF (Server-Side Request Forgery) protection utilities
*/
/**
* Check if URL points to private/internal network
* Blocks: localhost, private IPs, link-local, AWS metadata service
*/
export function isPrivateUrl(urlString: string): boolean {
try {
const url = new URL(urlString)
// Strip a trailing dot so FQDN forms like "localhost." (which still
// resolve to 127.0.0.1) cannot bypass the equality checks below.
const hostname = url.hostname.toLowerCase().replace(/\.$/, "")
// Block localhost
if (
hostname === "localhost" ||
hostname === "127.0.0.1" ||
hostname === "::1"
) {
return true
}
// Block AWS/cloud metadata endpoints
if (
hostname === "169.254.169.254" ||
hostname === "metadata.google.internal"
) {
return true
}
// Check for private IPv4 ranges
const ipv4Match = hostname.match(
/^(\d{1,3})\.(\d{1,3})\.(\d{1,3})\.(\d{1,3})$/,
)
if (ipv4Match) {
const [, a, b] = ipv4Match.map(Number)
if (a === 10) return true // 10.0.0.0/8
if (a === 172 && b >= 16 && b <= 31) return true // 172.16.0.0/12
if (a === 192 && b === 168) return true // 192.168.0.0/16
if (a === 169 && b === 254) return true // 169.254.0.0/16 (link-local)
if (a === 127) return true // 127.0.0.0/8 (loopback)
}
// Block common internal hostnames
if (
hostname.endsWith(".local") ||
hostname.endsWith(".internal") ||
hostname.endsWith(".localhost")
) {
return true
}
return false
} catch {
return true // Invalid URL - block it
}
}
/**
* Whether private URLs are allowed (defaults to true)
* Set ALLOW_PRIVATE_URLS=false to block private URLs
*/
export const allowPrivateUrls = process.env.ALLOW_PRIVATE_URLS !== "false"