diff --git a/meta/recipes-devtools/go/go-1.22.12.inc b/meta/recipes-devtools/go/go-1.22.12.inc
index 03a1a81fc3..ba4fe9a734 100644
--- a/meta/recipes-devtools/go/go-1.22.12.inc
+++ b/meta/recipes-devtools/go/go-1.22.12.inc
@@ -53,6 +53,7 @@ SRC_URI += "\
     file://CVE-2026-39826.patch \
     file://CVE-2026-42499.patch \
     file://CVE-2026-42501.patch \
+    file://CVE-2026-42504.patch \
 "
 SRC_URI[main.sha256sum] = "012a7e1f37f362c0918c1dfa3334458ac2da1628c4b9cf4d9ca02db986e17d71"
 
diff --git a/meta/recipes-devtools/go/go/CVE-2026-42504.patch b/meta/recipes-devtools/go/go/CVE-2026-42504.patch
new file mode 100644
index 0000000000..1ae104ae19
--- /dev/null
+++ b/meta/recipes-devtools/go/go/CVE-2026-42504.patch
@@ -0,0 +1,58 @@
+From 41ca50d68cd74e0a68f3917cd902885c84fedbf7 Mon Sep 17 00:00:00 2001
+From: Damien Neil <dneil@google.com>
+Date: Tue, 5 May 2026 15:20:34 -0700
+Subject: [PATCH] mime: avoid quadratic complexity in WordDecoder.DecodeHeader
+
+When encountering an undecodable encoded-word,
+skip over the entire word rather than just the initial "=?".
+
+Fixes #79217
+Fixes CVE-2026-42504
+
+Change-Id: I28605faa235459d2ba71bd0f3ae3dce96a6a6964
+Reviewed-on: https://go-review.googlesource.com/c/go/+/774481
+Reviewed-by: Nicholas Husin <nsh@golang.org>
+LUCI-TryBot-Result: golang-scoped@luci-project-accounts.iam.gserviceaccount.com <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
+Reviewed-by: Nicholas Husin <husin@google.com>
+
+CVE: CVE-2026-42504
+Upstream-Status: Backport [https://github.com/golang/go/commit/f230dd8a1d0a63d73e92685e378dcd725f7aac00]
+Signed-off-by: Theo Gaige (Schneider Electric) <tgaige.opensource@witekio.com>
+---
+ src/mime/encodedword.go      | 4 ++--
+ src/mime/encodedword_test.go | 4 ++++
+ 2 files changed, 6 insertions(+), 2 deletions(-)
+
+diff --git a/src/mime/encodedword.go b/src/mime/encodedword.go
+index e6b470b1fb..a7059f3bc4 100644
+--- a/src/mime/encodedword.go
++++ b/src/mime/encodedword.go
+@@ -275,8 +275,8 @@ func (d *WordDecoder) DecodeHeader(header string) (string, error) {
+ 		content, err := decode(encoding, text)
+ 		if err != nil {
+ 			betweenWords = false
+-			buf.WriteString(header[:start+2])
+-			header = header[start+2:]
++			buf.WriteString(header[:end])
++			header = header[end:]
+ 			continue
+ 		}
+ 
+diff --git a/src/mime/encodedword_test.go b/src/mime/encodedword_test.go
+index 2a98794380..befc3cd996 100644
+--- a/src/mime/encodedword_test.go
++++ b/src/mime/encodedword_test.go
+@@ -140,6 +140,10 @@ func TestDecodeHeader(t *testing.T) {
+ 		{"=?ISO-8859-1?Q?a?=  =?ISO-8859-1?Q?b?=", "ab"},
+ 		{"=?ISO-8859-1?Q?a?= \r\n\t =?ISO-8859-1?Q?b?=", "ab"},
+ 		{"=?ISO-8859-1?Q?a_b?=", "a b"},
++		// Undecodable words
++		{"=?UTF-8?b?garbage?= =?UTF-8?b?QW5kcsOp?= =?UTF-8?b?garbage?=", "=?UTF-8?b?garbage?= André =?UTF-8?b?garbage?="},
++		{"=?UTF-8?b?QW5kcsOp", "=?UTF-8?b?QW5kcsOp"},
++		{"=?UTF-8?x?y?=?UTF-8?x?y=?", "=?UTF-8?x?y?=?UTF-8?x?y=?"},
+ 	}
+ 
+ 	for _, test := range tests {
+-- 
+2.43.0
+