CVE-2025-31135
MEDIUMCVSS Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Lifecycle Timeline
3Description
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.
Analysis
Go-Guerrilla SMTP Daemon is a lightweight SMTP server written in Go. Rated medium severity (CVSS 5.3), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
Technical Context
This vulnerability is classified under CWE-20. 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. Version information: Prior to 1.6.7.
Affected Products
See vendor advisory for affected versions.
Remediation
No vendor patch is available at time of analysis. Monitor vendor advisories for updates. Apply vendor patches when available. Implement network segmentation and monitoring as interim mitigations.
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External POC / Exploit Code
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