🛡️ Sentinel: [CRITICAL] Fix SSRF vulnerability in web_fetch tool#576
🛡️ Sentinel: [CRITICAL] Fix SSRF vulnerability in web_fetch tool#576mudcube wants to merge 1 commit into
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🚨 Severity: CRITICAL 💡 Vulnerability: The `web_fetch` tool used `reqwest::blocking::get` without any validation of the target URL or IPs, allowing it to fetch arbitrary internal network resources, rendering it vulnerable to Server-Side Request Forgery (SSRF) and Time-of-Check to Time-of-Use (TOCTOU) DNS Rebinding attacks. 🎯 Impact: Attackers could trick the server into interacting with internal network services (e.g. metadata servers, internal databases) or bypassing external firewalls. 🔧 Fix: - Added `is_allowed_ip` helper function to block loopback, private networks, unspecified, multicast, broadcast, and link-local IPs across both IPv4 and IPv6. - Overhauled `handle_web_fetch` to manually resolve DNS, validate *all* returned IPs against the blocklist, and pin the validated IP to the HTTP client using `reqwest::blocking::ClientBuilder::resolve`. - Disabled automatic redirects and implemented manual redirect tracking (up to 5 redirects) through the same strict validation pipeline. ✅ Verification: `cargo test --package mill-plugin-system` passed. Tested with internal IPs (127.0.0.1) which are now successfully blocked. Recorded the vulnerability pattern in `.jules/sentinel.md`. Co-authored-by: mudcube <101564+mudcube@users.noreply.github.com>
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| || o[0] == 10 | ||
| || o[0] == 127 | ||
| || (o[0] == 169 && o[1] == 254) | ||
| || (o[0] == 172 && (16..=31).contains(&o[1])) | ||
| || (o[0] == 192 && o[1] == 168) |
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In environments that use carrier-grade/shared address space internally, URLs such as http://100.64.0.1/ still pass this predicate because 100.64.0.0/10 is not included in the disallowed IPv4 ranges. That leaves a practical SSRF path to non-public infrastructure even though the new resolver guard is meant to reject internal or otherwise non-routable targets; prefer denying all non-global/special-use IPv4 ranges rather than only RFC1918 plus a few others.
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🛡️ Sentinel: [CRITICAL] Fix SSRF vulnerability in web_fetch tool
🚨 Severity: CRITICAL
💡 Vulnerability: The
web_fetchtool usedreqwest::blocking::getwithout any validation of the target URL or IPs, allowing it to fetch arbitrary internal network resources, rendering it vulnerable to Server-Side Request Forgery (SSRF) and Time-of-Check to Time-of-Use (TOCTOU) DNS Rebinding attacks.🎯 Impact: Attackers could trick the server into interacting with internal network services (e.g. metadata servers, internal databases) or bypassing external firewalls.
🔧 Fix:
is_allowed_iphelper function to block loopback, private networks, unspecified, multicast, broadcast, and link-local IPs across both IPv4 and IPv6.handle_web_fetchto manually resolve DNS, validate all returned IPs against the blocklist, and pin the validated IP to the HTTP client usingreqwest::blocking::ClientBuilder::resolve.✅ Verification:
cargo test --package mill-plugin-systempassed. Tested with internal IPs (127.0.0.1) which are now successfully blocked. Recorded the vulnerability pattern in.jules/sentinel.md.PR created automatically by Jules for task 15401487702068249879 started by @mudcube