The SSRF filter checked ipv4_mapped? but not ipv4_compat?, allowing
addresses like ::169.254.169.254 to bypass the link-local check and
reach cloud metadata endpoints.
Changes:
- Add ipv4_compat? check to block deprecated IPv4-compatible format
- Rename private_address? to blocked_address? (more accurate - method
blocks more than just RFC 1918 private ranges)
- Add IPv6 test coverage for both mapped and compat formats
Both ipv4_mapped and ipv4_compat formats are blocked entirely as
defense-in-depth: DNS never returns these formats, so they only
appear in attack scenarios.
HackerOne: #3481701
Jeremy Daer
0eefd67b68