CVE-2025-31135CWE-20

Go-Guerrilla SMTP Daemon allows the PROXY command to be sent multiple times

Medium · published April 1, 2025

CVSS v3.1
5.3
EPSS
0%
Percentile
30.6
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v3.1
5.3 · MEDIUM
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
CVSS v4.0
Not supplied
EPSS
0.00378 · 30.6th percentile
Weakness
CWE-20 · Improper Input Validation
Published
2025-04-01T22:03Z
EPSS history
Timeline
  • 01 APR 22:03Z
    Go-Guerrilla SMTP Daemon allows the PROXY command to be sent multiple times
    cvelistv5