CVE-2025-31135 Information

Description

Go-Guerrilla SMTP Daemon is a lightweight SMTP server written in Go. Prior to 1.6.7 when ProxyOn is enabled the PROXY command will be accepted multiple times with later invocations overriding earlier ones. The proxy protocol only supports one initial PROXY header; anything after that is considered part of the exchange between client and server so the client is free to send further PROXY commands with whatever data it pleases. go-guerrilla will treat these as coming from the reverse proxy allowing a client to spoof its IP address. This vulnerability is fixed in 1.6.7.

Reference

https://github.com/phires/go-guerrilla/commit/7673947f2d5204a135d7ae0b7f80759e548abee6 https://github.com/phires/go-guerrilla/security/advisories/GHSA-c2c3-pqw5-5p7c