🛡️ Sentinel: [HIGH] Fix SSRF bypass via SIIT (IPv4-translated) addresses

[ManupaKDU]

🛡️ Sentinel: [HIGH] Fix SSRF bypass via SIIT (IPv4-translated) addresses

🚨 Severity: HIGH
💡 Vulnerability: Python's ipaddress module evaluates SIIT (IPv4-translated) addresses (e.g., ::ffff:0:a.b.c.d) as is_global = True and does not expose them via the ipv4_mapped property. This allows an attacker to bypass standard SSRF filters by embedding loopback or private IPv4 addresses within the SIIT IPv6 structure, which the host OS network stack may then natively unwrap and route.
🎯 Impact: Attackers could bypass SSRF protections to scan or interact with internal/private IPs and the loopback interface on the host machine.
🔧 Fix: Updated the manual IPv6 unpacking block in testping1.py to identify the SIIT prefix by checking if the high 96 bits equal 0xffff0000 (ip_int >> 32 == 0xffff0000). When matched, the embedded 32-bit IPv4 address is extracted and correctly subjected to the SSRF blocklist validation.
✅ Verification: Added a test case test_is_reachable_ssrf_bypass_siit that ensures ::ffff:0:127.0.0.1 and ::ffff:0:192.168.1.1 are correctly rejected. Verified by running the test suite (python3 -m unittest test_testping1.py).

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PR created automatically by Jules for task 12756634130325821454 started by @ManupaKDU

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