🛡️ Sentinel: Fix SSRF via DNS Resolution by google-labs-jules[bot] · Pull Request #103 · abhimehro/ctrld-sync

google-labs-jules · 2026-01-15T10:42:23Z

🛡️ Sentinel: [HIGH] Fix SSRF via DNS Resolution

🚨 Severity: HIGH
💡 Vulnerability: The previous validation logic checked for private IP literals but allowed domain names that resolve to private IPs (e.g., localtest.me -> 127.0.0.1), enabling SSRF attacks against internal services.
🎯 Impact: An attacker could supply a malicious folder URL that points to internal network resources, potentially accessing sensitive internal APIs or metadata services.
🔧 Fix: Added DNS resolution step to validate_folder_url. Now resolves the hostname and checks if the underlying IP is private/loopback using socket.getaddrinfo and ipaddress.
✅ Verification: Verified using a reproduction script reproduce_ssrf.py (deleted before submit) which confirmed localtest.me is now blocked. Ran dry-run to ensure normal functionality is preserved.

PR created automatically by Jules for task 931545182998519987 started by @abhimehro

Enhances `validate_folder_url` to resolve hostnames to IP addresses and check them against private/loopback ranges. This prevents SSRF attacks that use public domain names pointing to internal IP addresses (e.g., DNS rebinding or simple resolution to private IPs). - Import `socket` module. - Use `socket.getaddrinfo` to resolve hostnames. - Verify resolved IPs using `ipaddress` module. - Fail validation if any resolved IP is private or loopback.

google-labs-jules · 2026-01-15T10:42:24Z

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trunk-io · 2026-01-15T10:42:27Z

Merging to main in this repository is managed by Trunk.

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main.py

+            try:
+                # Use getaddrinfo to support both IPv4 and IPv6
+                addr_infos = socket.getaddrinfo(hostname, None)
+                for family, type, proto, canonname, sockaddr in addr_infos:


main.py

+            try:
+                # Use getaddrinfo to support both IPv4 and IPv6
+                addr_infos = socket.getaddrinfo(hostname, None)
+                for family, type, proto, canonname, sockaddr in addr_infos:


main.py

+
+                    ip = ipaddress.ip_address(ip_str)
+                    if ip.is_private or ip.is_loopback:
+                        log.warning(f"Skipping unsafe URL (domain resolves to private IP {ip_str}): {sanitize_for_log(url)}")


main.py

+                        log.warning(f"Skipping unsafe URL (domain resolves to private IP {ip_str}): {sanitize_for_log(url)}")
+                        return False
+            except socket.gaierror:
+                log.warning(f"Could not resolve hostname for validation: {sanitize_for_log(hostname)}")


main.py

+                log.warning(f"Could not resolve hostname for validation: {sanitize_for_log(hostname)}")
+                return False
+            except Exception as e:
+                log.warning(f"Error during DNS resolution check: {e}")


.jules/sentinel.md

-## 2025-01-21 - [SSRF Protection and Input Limits]
-**Vulnerability:** The `folder_url` validation checked for HTTPS but allowed internal IP addresses (e.g., `127.0.0.1`, `10.0.0.0/8`). This could theoretically allow Server-Side Request Forgery (SSRF) if the script is run in an environment with access to sensitive internal services. Additionally, `profile_id` had no length limit.
-**Learning:** HTTPS validation alone is insufficient to prevent SSRF against internal services that might support HTTPS or use self-signed certs (if verification was disabled or bypassed). Explicitly blocking private IP ranges provides necessary defense-in-depth.
+## 2025-01-21 - [SSRF Protection via DNS Resolution]


.jules/sentinel.md

-## 2025-01-21 - [SSRF Protection and Input Limits]
-**Vulnerability:** The `folder_url` validation checked for HTTPS but allowed internal IP addresses (e.g., `127.0.0.1`, `10.0.0.0/8`). This could theoretically allow Server-Side Request Forgery (SSRF) if the script is run in an environment with access to sensitive internal services. Additionally, `profile_id` had no length limit.
-**Learning:** HTTPS validation alone is insufficient to prevent SSRF against internal services that might support HTTPS or use self-signed certs (if verification was disabled or bypassed). Explicitly blocking private IP ranges provides necessary defense-in-depth.
+## 2025-01-21 - [SSRF Protection via DNS Resolution]


main.py

+                    if '%' in ip_str:
+                        ip_str = ip_str.split('%')[0]
+
+                    ip = ipaddress.ip_address(ip_str)


main.py

+
+                    ip = ipaddress.ip_address(ip_str)
+                    if ip.is_private or ip.is_loopback:
+                        log.warning(f"Skipping unsafe URL (domain resolves to private IP {ip_str}): {sanitize_for_log(url)}")


main.py

+                        log.warning(f"Skipping unsafe URL (domain resolves to private IP {ip_str}): {sanitize_for_log(url)}")
+                        return False
+            except socket.gaierror:
+                log.warning(f"Could not resolve hostname for validation: {sanitize_for_log(hostname)}")


main.py

+            try:
+                # Use getaddrinfo to support both IPv4 and IPv6
+                addr_infos = socket.getaddrinfo(hostname, None)
+                for family, type, proto, canonname, sockaddr in addr_infos:


main.py

+            try:
+                # Use getaddrinfo to support both IPv4 and IPv6
+                addr_infos = socket.getaddrinfo(hostname, None)
+                for family, type, proto, canonname, sockaddr in addr_infos:


main.py

+            try:
+                # Use getaddrinfo to support both IPv4 and IPv6
+                addr_infos = socket.getaddrinfo(hostname, None)
+                for family, type, proto, canonname, sockaddr in addr_infos:


main.py

+            try:
+                # Use getaddrinfo to support both IPv4 and IPv6
+                addr_infos = socket.getaddrinfo(hostname, None)
+                for family, type, proto, canonname, sockaddr in addr_infos:


main.py

+            try:
+                # Use getaddrinfo to support both IPv4 and IPv6
+                addr_infos = socket.getaddrinfo(hostname, None)
+                for family, type, proto, canonname, sockaddr in addr_infos:


main.py

+            except socket.gaierror:
+                log.warning(f"Could not resolve hostname for validation: {sanitize_for_log(hostname)}")
+                return False
+            except Exception as e:


main.py

+                    if '%' in ip_str:
+                        ip_str = ip_str.split('%')[0]
+
+                    ip = ipaddress.ip_address(ip_str)


main.py

+
+                    ip = ipaddress.ip_address(ip_str)
+                    if ip.is_private or ip.is_loopback:
+                        log.warning(f"Skipping unsafe URL (domain resolves to private IP {ip_str}): {sanitize_for_log(url)}")


main.py

+                        log.warning(f"Skipping unsafe URL (domain resolves to private IP {ip_str}): {sanitize_for_log(url)}")
+                        return False
+            except socket.gaierror:
+                log.warning(f"Could not resolve hostname for validation: {sanitize_for_log(hostname)}")


main.py

+            except socket.gaierror:
+                log.warning(f"Could not resolve hostname for validation: {sanitize_for_log(hostname)}")
+                return False
+            except Exception as e:


main.py

+            try:
+                # Use getaddrinfo to support both IPv4 and IPv6
+                addr_infos = socket.getaddrinfo(hostname, None)
+                for family, type, proto, canonname, sockaddr in addr_infos:


main.py

+            try:
+                # Use getaddrinfo to support both IPv4 and IPv6
+                addr_infos = socket.getaddrinfo(hostname, None)
+                for family, type, proto, canonname, sockaddr in addr_infos:


main.py

+
+                    ip = ipaddress.ip_address(ip_str)
+                    if ip.is_private or ip.is_loopback:
+                        log.warning(f"Skipping unsafe URL (domain resolves to private IP {ip_str}): {sanitize_for_log(url)}")


main.py

+                        log.warning(f"Skipping unsafe URL (domain resolves to private IP {ip_str}): {sanitize_for_log(url)}")
+                        return False
+            except socket.gaierror:
+                log.warning(f"Could not resolve hostname for validation: {sanitize_for_log(hostname)}")


main.py

+            except socket.gaierror:
+                log.warning(f"Could not resolve hostname for validation: {sanitize_for_log(hostname)}")
+                return False
+            except Exception as e:


main.py

+                log.warning(f"Could not resolve hostname for validation: {sanitize_for_log(hostname)}")
+                return False
+            except Exception as e:
+                log.warning(f"Error during DNS resolution check: {e}")


abhimehro · 2026-01-18T21:23:14Z

Superseded: SSRF DNS resolution fix already in main via PR #109.

google-labs-jules · 2026-01-18T21:24:27Z

Superseded: SSRF DNS resolution fix already in main via PR #109.

Understood. Acknowledging that this work is now obsolete and stopping work on this task.

github-actions bot added the python label Jan 15, 2026

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