From da8eb3ece8626c68bec931c7d54b112588474524 Mon Sep 17 00:00:00 2001
From: Ralph Slooten <axllent@gmail.com>
Date: Sat, 9 May 2026 17:13:22 +1200
Subject: [PATCH] Fix: Validate SMTP XCLIENT args before processing

---
 internal/smtpd/smtpd.go | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/internal/smtpd/smtpd.go b/internal/smtpd/smtpd.go
index 1915f81..7f5cd6f 100644
--- a/internal/smtpd/smtpd.go
+++ b/internal/smtpd/smtpd.go
@@ -639,6 +639,9 @@ loop:
 				xCArgs := strings.SplitSeq(args, " ")
 				for xCArg := range xCArgs {
 					xCParse := strings.Split(strings.TrimSpace(xCArg), "=")
+					if len(xCParse) != 2 {
+						continue
+					}
 					if strings.ToUpper(xCParse[0]) == "ADDR" && (net.ParseIP(xCParse[1]) != nil) {
 						s.xClientADDR = xCParse[1]
 					}