From 14c3e2d9d948837a35aff984646bf55a9a225b33 Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@koston.org>
Date: Thu, 12 Mar 2026 07:16:53 -1000
Subject: [PATCH] [api] Fix heap-buffer-overflow in protobuf message dump for
 StringRef (#14721)

---
 esphome/components/api/api_pb2_dump.cpp | 2 +-
 script/api_protobuf/api_protobuf.py     | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/esphome/components/api/api_pb2_dump.cpp b/esphome/components/api/api_pb2_dump.cpp
index 740bf2e47f..5a53f0281f 100644
--- a/esphome/components/api/api_pb2_dump.cpp
+++ b/esphome/components/api/api_pb2_dump.cpp
@@ -13,7 +13,7 @@ namespace esphome::api {
 static inline void append_quoted_string(DumpBuffer &out, const StringRef &ref) {
   out.append("'");
   if (!ref.empty()) {
-    out.append(ref.c_str());
+    out.append(ref.c_str(), ref.size());
   }
   out.append("'");
 }
diff --git a/script/api_protobuf/api_protobuf.py b/script/api_protobuf/api_protobuf.py
index b4044c362c..dff6c7690a 100755
--- a/script/api_protobuf/api_protobuf.py
+++ b/script/api_protobuf/api_protobuf.py
@@ -642,7 +642,7 @@ class StringType(TypeInfo):
         # For SOURCE_BOTH, check if StringRef is set (sending) or use string (received)
         return (
             f"if (!this->{self.field_name}_ref_.empty()) {{"
-            f'  out.append("\'").append(this->{self.field_name}_ref_.c_str()).append("\'");'
+            f'  out.append("\'").append(this->{self.field_name}_ref_.c_str(), this->{self.field_name}_ref_.size()).append("\'");'
             f"}} else {{"
             f'  out.append("\'").append(this->{self.field_name}).append("\'");'
             f"}}"
@@ -2705,7 +2705,7 @@ namespace esphome::api {
 static inline void append_quoted_string(DumpBuffer &out, const StringRef &ref) {
   out.append("'");
   if (!ref.empty()) {
-    out.append(ref.c_str());
+    out.append(ref.c_str(), ref.size());
   }
   out.append("'");
 }