A flaw was found in the ip-address library. This vulnerability allows a remote attacker to bypass security restrictions, such as Internet Protocol (IP) allowlists or denylists. The library's subnet containment checks fail to verify whether the compared addresses belong to the same address family, comparing IPv4 and IPv6 addresses as if they shared an address space. As a result, an attacker can provide an address from a different IP family with matching leading bits, causing an unauthorized address outside the intended range to be treated as valid.
Last checked: 2026-09-30 21:40 UTC
Proof of concept · CISA Coordinator (Assessed 2026-09-28 19:13 UTC)
Fix evidence last checked: 2026-09-28 19:04 UTC