From 7b5a4b466a135ab658317e928830a65c05f9d19a Mon Sep 17 00:00:00 2001
From: Jonathan Swoboda <154711427+swoboda1337@users.noreply.github.com>
Date: Wed, 25 Mar 2026 16:50:37 -0400
Subject: [PATCH] [uart] Fix debug callback missing peeked byte and reading
 past end (#15169)

---
 esphome/components/uart/uart_component_esp_idf.cpp | 6 ++++--
 esphome/components/uart/uart_component_host.cpp    | 6 ++----
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/esphome/components/uart/uart_component_esp_idf.cpp b/esphome/components/uart/uart_component_esp_idf.cpp
index 8168e49805..82120b1a5f 100644
--- a/esphome/components/uart/uart_component_esp_idf.cpp
+++ b/esphome/components/uart/uart_component_esp_idf.cpp
@@ -324,6 +324,9 @@ bool IDFUARTComponent::peek_byte(uint8_t *data) {
 }
 
 bool IDFUARTComponent::read_array(uint8_t *data, size_t len) {
+  if (len == 0) {
+    return false;
+  }
   size_t length_to_read = len;
   int32_t read_len = 0;
   if (!this->check_read_timeout_(len))
@@ -331,11 +334,10 @@ bool IDFUARTComponent::read_array(uint8_t *data, size_t len) {
   if (this->has_peek_) {
     length_to_read--;
     *data = this->peek_byte_;
-    data++;
     this->has_peek_ = false;
   }
   if (length_to_read > 0)
-    read_len = uart_read_bytes(this->uart_num_, data, length_to_read, 20 / portTICK_PERIOD_MS);
+    read_len = uart_read_bytes(this->uart_num_, data + (len - length_to_read), length_to_read, 20 / portTICK_PERIOD_MS);
 #ifdef USE_UART_DEBUGGER
   for (size_t i = 0; i < len; i++) {
     this->debug_callback_.call(UART_DIRECTION_RX, data[i]);
diff --git a/esphome/components/uart/uart_component_host.cpp b/esphome/components/uart/uart_component_host.cpp
index 66026f3ccd..e9c101816e 100644
--- a/esphome/components/uart/uart_component_host.cpp
+++ b/esphome/components/uart/uart_component_host.cpp
@@ -235,16 +235,14 @@ bool HostUartComponent::read_array(uint8_t *data, size_t len) {
   }
   if (!this->check_read_timeout_(len))
     return false;
-  uint8_t *data_ptr = data;
   size_t length_to_read = len;
   if (this->has_peek_) {
     length_to_read--;
-    *data_ptr = this->peek_byte_;
-    data_ptr++;
+    *data = this->peek_byte_;
     this->has_peek_ = false;
   }
   if (length_to_read > 0) {
-    int sz = ::read(this->file_descriptor_, data_ptr, length_to_read);
+    int sz = ::read(this->file_descriptor_, data + (len - length_to_read), length_to_read);
     if (sz == -1) {
       this->update_error_(strerror(errno));
       return false;