diff --git a/NEWS b/NEWS
index 84bbf47ee39..ac76176680c 100644
--- a/NEWS
+++ b/NEWS
@@ -20,6 +20,10 @@ PHP                                                                        NEWS
   . Fixed GH-11982 (str_getcsv returns null byte for unterminated enclosure).
     (Jakub Zelenka)
 
+- Streams:
+  . Fixed bug #52335 (fseek() on memory stream behavior different than file).
+    (Jakub Zelenka)
+
 17 Aug 2023, PHP 8.3.0beta3
 
 - Core:
diff --git a/UPGRADING b/UPGRADING
index 20ff98b3095..eec2b433219 100644
--- a/UPGRADING
+++ b/UPGRADING
@@ -648,6 +648,9 @@ PHP 8.3 UPGRADE NOTES
 - Streams:
   . Blocking fread() on socket connection returns immediately if there are
     any buffered data instead of waiting for more data.
+  . Memory stream no longer fails if seek offset is past the end. Instead
+    the memory is increase on the next write and date between the old end and
+    offset is filled with zero bytes in the same way how it works for files.
 
 ========================================
 14. Performance Improvements
diff --git a/ext/standard/tests/file/bug52335.phpt b/ext/standard/tests/file/bug52335.phpt
new file mode 100644
index 00000000000..8a7cbb53fcf
--- /dev/null
+++ b/ext/standard/tests/file/bug52335.phpt
@@ -0,0 +1,67 @@
+--TEST--
+Bug #52335 (fseek() on memory stream behavior different then file)
+--FILE--
+<?php
+
+echo "Read mode\n";
+$fpr = fopen("php://memory", "r");
+var_dump(fseek($fpr, 20));
+var_dump(feof($fpr));
+var_dump(ftell($fpr));
+var_dump(feof($fpr));
+var_dump(fread($fpr, 2));
+var_dump(feof($fpr));
+var_dump(fseek($fpr, 24));
+var_dump(feof($fpr));
+var_dump(ftell($fpr));
+fclose($fpr);
+
+echo "Read write mode\n";
+$fprw = fopen("php://memory", "r+");
+var_dump(fwrite($fprw, "data"));
+var_dump(fseek($fprw, 20, SEEK_END));
+var_dump(feof($fprw));
+var_dump(ftell($fprw));
+var_dump(feof($fprw));
+var_dump(fread($fprw, 2));
+var_dump(feof($fprw));
+var_dump(fseek($fprw, 20));
+var_dump(fwrite($fprw, " and more data"));
+var_dump(feof($fprw));
+var_dump(ftell($fprw));
+var_dump(fread($fprw, 10));
+var_dump(fseek($fprw, 16, SEEK_CUR));
+var_dump(ftell($fprw));
+var_dump(fseek($fprw, 0));
+var_dump(bin2hex(stream_get_contents($fprw)));
+fclose($fprw);
+
+?>
+--EXPECT--
+Read mode
+int(0)
+bool(false)
+int(20)
+bool(false)
+string(0) ""
+bool(true)
+int(0)
+bool(false)
+int(24)
+Read write mode
+int(4)
+int(0)
+bool(false)
+int(24)
+bool(false)
+string(0) ""
+bool(true)
+int(0)
+int(14)
+bool(false)
+int(34)
+string(0) ""
+int(0)
+int(50)
+int(0)
+string(68) "646174610000000000000000000000000000000020616e64206d6f72652064617461"
diff --git a/ext/standard/tests/file/gh9441.phpt b/ext/standard/tests/file/gh9441.phpt
new file mode 100644
index 00000000000..0c32e2b1c69
--- /dev/null
+++ b/ext/standard/tests/file/gh9441.phpt
@@ -0,0 +1,20 @@
+--TEST--
+Bug GH-9441 (fseek does not work with php://input when data is not preread)
+--INI--
+enable_post_data_reading=0
+--POST_RAW--
+Content-Type: application/unknown
+a=123456789&b=ZYX
+--FILE--
+<?php
+$input = fopen("php://input", "r");
+var_dump(fseek($input, 10));
+var_dump(ftell($input));
+var_dump(fread($input, 10));
+var_dump(file_get_contents("php://input"));
+?>
+--EXPECT--
+int(0)
+int(10)
+string(7) "9&b=ZYX"
+string(17) "a=123456789&b=ZYX"
diff --git a/ext/standard/tests/file/stream_rfc2397_007.phpt b/ext/standard/tests/file/stream_rfc2397_007.phpt
index 56d91621575..dcbe5beeb3d 100644
--- a/ext/standard/tests/file/stream_rfc2397_007.phpt
+++ b/ext/standard/tests/file/stream_rfc2397_007.phpt
@@ -125,8 +125,8 @@ int(0)
 int(3)
 bool(false)
 ===S:10,C===
-int(-1)
-bool(false)
+int(0)
+int(13)
 bool(false)
 ===S:-1,E===
 int(0)
@@ -137,6 +137,6 @@ int(0)
 int(6)
 bool(false)
 ===S:1,E===
-int(-1)
-bool(false)
+int(0)
+int(7)
 bool(false)
diff --git a/main/streams/memory.c b/main/streams/memory.c
index 444f9637617..62d36906635 100644
--- a/main/streams/memory.c
+++ b/main/streams/memory.c
@@ -49,11 +49,17 @@ static ssize_t php_stream_memory_write(php_stream *stream, const char *buf, size
 
 	if (ms->mode & TEMP_STREAM_READONLY) {
 		return (ssize_t) -1;
-	} else if (ms->mode & TEMP_STREAM_APPEND) {
-		ms->fpos = ZSTR_LEN(ms->data);
 	}
-	if (ms->fpos + count > ZSTR_LEN(ms->data)) {
+	size_t data_len = ZSTR_LEN(ms->data);
+	if (ms->mode & TEMP_STREAM_APPEND) {
+		ms->fpos = data_len;
+	}
+	if (ms->fpos + count > data_len) {
 		ms->data = zend_string_realloc(ms->data, ms->fpos + count, 0);
+		if (ms->fpos > data_len) {
+			/* zero the bytes added due to seek past end position */
+			memset(ZSTR_VAL(ms->data) + data_len, 0, ms->fpos - data_len);
+		}
 	} else {
 		ms->data = zend_string_separate(ms->data, 0);
 	}
@@ -73,7 +79,7 @@ static ssize_t php_stream_memory_read(php_stream *stream, char *buf, size_t coun
 	php_stream_memory_data *ms = (php_stream_memory_data*)stream->abstract;
 	assert(ms != NULL);
 
-	if (ms->fpos == ZSTR_LEN(ms->data)) {
+	if (ms->fpos >= ZSTR_LEN(ms->data)) {
 		stream->eof = 1;
 		count = 0;
 	} else {
@@ -132,20 +138,14 @@ static int php_stream_memory_seek(php_stream *stream, zend_off_t offset, int whe
 					return 0;
 				}
 			} else {
-				if (ms->fpos + (size_t)(offset) > ZSTR_LEN(ms->data)) {
-					ms->fpos = ZSTR_LEN(ms->data);
-					*newoffs = -1;
-					return -1;
-				} else {
-					ms->fpos = ms->fpos + offset;
-					*newoffs = ms->fpos;
-					stream->eof = 0;
-					return 0;
-				}
+				stream->eof = 0;
+				ms->fpos = ms->fpos + offset;
+				*newoffs = ms->fpos;
+				return 0;
 			}
 		case SEEK_SET:
-			if (ZSTR_LEN(ms->data) < (size_t)(offset)) {
-				ms->fpos = ZSTR_LEN(ms->data);
+			if (offset < 0) {
+				ms->fpos = 0;
 				*newoffs = -1;
 				return -1;
 			} else {
@@ -156,9 +156,10 @@ static int php_stream_memory_seek(php_stream *stream, zend_off_t offset, int whe
 			}
 		case SEEK_END:
 			if (offset > 0) {
-				ms->fpos = ZSTR_LEN(ms->data);
-				*newoffs = -1;
-				return -1;
+				ms->fpos = ZSTR_LEN(ms->data) + offset;
+				*newoffs = ms->fpos;
+				stream->eof = 0;
+				return 0;
 			} else if (ZSTR_LEN(ms->data) < (size_t)(-offset)) {
 				ms->fpos = 0;
 				*newoffs = -1;