Flowise: SSRF Protection Bypass via IPv4-Mapped IPv6 Addresses

Flowise is a drag & drop user interface to build a customized large language model flow. Prior to 3.1.3, Flowise's HTTP security module httpSecurity.ts did not normalize IPv4-mapped IPv6 addresses such as ::ffff:127.0.0.1 and ::ffff:169.254.169.254 before checking them against the deny list. Because ipaddr.js reports these addresses as ipv6 while IPv4 CIDR deny-list entries are ipv4, isDeniedIP() skipped the IPv4 CIDR checks. An attacker who controls DNS resolution for a hostname used by the HTTP Node, API Chain, Document Loader, MCP tool, or other paths using secureAxiosRequest(), secureFetch(), or checkDenyList() could return a AAAA record for an IPv4-mapped target and cause requests to reach localhost, internal services, or cloud metadata endpoints. This issue is fixed in version 3.1.3.

Source published

4 Aug 2026 15:51:47 UTC

Source modified

4 Aug 2026 16:36:51 UTC

Observed here

23 Oct 2026 15:48:27 UTC

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CVSS 4.0 · 7.6 CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:L/SC:N/SI:N/SA:N