From ee6db3d78c23c3d453be4c38f0e450a457d71c7d Mon Sep 17 00:00:00 2001
From: Sebastian Turner <sebastiant3484@gmail.com>
Date: Mon, 19 Oct 2026 08:32:51 -0700
Subject: [PATCH] Fix quoted_printable_encode() exceeding the line length for
 bytes 0xF5 to 0xFF

Signed-off-by: Sebastian Turner <sebastiant3484@gmail.com>
---
 ext/standard/quot_print.c                     |  2 +-
 .../quoted_printable_encode_line_length.phpt  | 20 +++++++++++++++++++
 2 files changed, 21 insertions(+), 1 deletion(-)
 create mode 100644 ext/standard/tests/strings/quoted_printable_encode_line_length.phpt

diff --git a/ext/standard/quot_print.c b/ext/standard/quot_print.c
index 75606c44a980..0fc8c27343c9 100644
--- a/ext/standard/quot_print.c
+++ b/ext/standard/quot_print.c
@@ -155,7 +155,7 @@ PHPAPI zend_string *php_quot_print_encode(const unsigned char *str, size_t lengt
 			lp = 0;
 		} else {
 			if (iscntrl (c) || (c == 0x7f) || (c & 0x80) || (c == '=') || ((c == ' ') && (*str == '\015'))) {
-				if ((((lp+= 3) > PHP_QPRINT_MAXL) && (c <= 0x7f))
+				if ((((lp+= 3) > PHP_QPRINT_MAXL) && ((c <= 0x7f) || (c > 0xf4)))
 				    || ((c > 0x7f) && (c <= 0xdf) && ((lp + 3) > PHP_QPRINT_MAXL))
 				    || ((c > 0xdf) && (c <= 0xef) && ((lp + 6) > PHP_QPRINT_MAXL))
 				    || ((c > 0xef) && (c <= 0xf4) && ((lp + 9) > PHP_QPRINT_MAXL))) {
diff --git a/ext/standard/tests/strings/quoted_printable_encode_line_length.phpt b/ext/standard/tests/strings/quoted_printable_encode_line_length.phpt
new file mode 100644
index 000000000000..b7cd09b52a64
--- /dev/null
+++ b/ext/standard/tests/strings/quoted_printable_encode_line_length.phpt
@@ -0,0 +1,20 @@
+--TEST--
+quoted_printable_encode() keeps lines within 76 characters for bytes 0xF5 to 0xFF
+--FILE--
+<?php
+
+foreach (["\xF5", "\xF8", "\xFF"] as $byte) {
+    $str = str_repeat($byte, 30);
+    $encoded = quoted_printable_encode($str);
+    echo bin2hex($byte), ": ", implode(",", array_map('strlen', explode("\r\n", $encoded))), "\n";
+    var_dump(quoted_printable_decode($encoded) === $str);
+}
+
+?>
+--EXPECT--
+f5: 76,15
+bool(true)
+f8: 76,15
+bool(true)
+ff: 76,15
+bool(true)