From e715696bd7f6fdca8137c4f8c573fef08223a77b Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@home-assistant.io>
Date: Tue, 8 Sep 2026 04:15:24 +0200
Subject: [PATCH] [core] Bound StringRef's JSON conversion by the view length

---
 esphome/core/string_ref.h | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/esphome/core/string_ref.h b/esphome/core/string_ref.h
index 0c4a1d3fa8..ca6368d956 100644
--- a/esphome/core/string_ref.h
+++ b/esphome/core/string_ref.h
@@ -263,7 +263,14 @@ inline double stod(const StringRef &str, size_t *pos = nullptr) {
 
 #ifdef USE_JSON
 // NOLINTNEXTLINE(readability-identifier-naming)
-inline void convertToJson(const StringRef &src, JsonVariant dst) { dst.set(src.empty() ? "" : src.c_str()); }
+inline void convertToJson(const StringRef &src, JsonVariant dst) {
+  // Bounded by the view length; a null, empty view becomes "" rather than JSON null
+  if (src.empty()) {
+    dst.set("");
+    return;
+  }
+  dst.set(JsonString(src.c_str(), src.size()));
+}
 #endif  // USE_JSON
 
 }  // namespace esphome