🛡️ Sentinel: [CRITICAL/HIGH] Fix SSRF bypass via ISATAP IPv6 addresses

[ManupaKDU]

🚨 Severity: HIGH
💡 Vulnerability: The application was vulnerable to an SSRF bypass when passed ISATAP tunneling addresses (e.g., 2001:db8::5efe:127.0.0.1 or 2001:db8::200:5efe:127.0.0.1), which encapsulate a blocked internal IPv4 address. Python's ipaddress module evaluates these addresses as is_global = True and does not provide an isatap property to easily extract the embedded IPv4 address.
🎯 Impact: An attacker could bypass SSRF protections to scan or interact with internal, private, or loopback network addresses by wrapping them in an ISATAP IPv6 address, circumventing the intended security boundaries.
🔧 Fix: Added manual unpacking logic for ISATAP (RFC 5214) addresses in testping1.py. Extracted the 32-bit ISATAP identifier using bitwise shifting ((ip_int >> 32) & 0xFFFFFFFF) to check for 0x00005efe or 0x02005efe. If identified, the underlying IPv4 address is extracted and validated against SSRF blocklist rules.
✅ Verification: Added the test test_is_reachable_ssrf_bypass_isatap in test_testping1.py which explicitly validates that ISATAP encapsulations of loopback and private IPs are rejected by the SSRF filter. All tests pass successfully.

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PR created automatically by Jules for task 13537170886671902071 started by @ManupaKDU

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