9router Search Proxy SSRF Protection Bypass Leading to Internal Network Probing and Authentication Failure
An attacker can pass a malicious provider_options.baseUrl parameter through the /v1/search endpoint and exploit multiple bypass techniques in the SSRF guard—including lack of DNS-resolution validation, defective IPv6-mapped address regex matching, ignoring trailing dots on hostnames, and failure to re-validate redirect targets—causing the server to issue requests to internal private networks or cloud metadata endpoints. Because requests toward loopback addresses are incorrectly marked by middleware as trusted local sources, an attacker can obtain keyless access to local /v1/* interfaces, steal upstream search provider API keys, and perform deep reconnaissance of internal services with sensitive data exfiltration.
- It is recommended to enforce a strict allowlist of IP addresses after DNS resolution of domain names, disable automatic redirects or recursively security-check redirect targets, fix the regex defect in IPv6 address normalization logic, and remove blacklist restrictions that rely only on string matching. In addition, never treat requests whose source IP is a loopback address as authenticated by default; enforce an independent authentication flow for local interface access to block privilege-escalation risks.
