From 12f55c2809507efe0a5741b9ec7fcb8338ff5c56 Mon Sep 17 00:00:00 2001
From: Heberti Almeida <hebertialmeida@gmail.com>
Date: Thu, 30 Oct 2025 12:18:52 -0300
Subject: [PATCH] Don't allow link destinations with unbalanced unescaped
 parentheses.

See https://github.com/commonmark/commonmark.js/issues/177
---
 src/inlines.c       |  7 ++++---
 test/regression.txt | 12 ++++++++++++
 2 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/src/inlines.c b/src/inlines.c
index 5fee895d6..fc6c09bb0 100644
--- a/src/inlines.c
+++ b/src/inlines.c
@@ -490,8 +490,9 @@ static int scan_delims(cmark_parser *parser, subject *subj, unsigned char c,
     *can_close = right_flanking &&
                  (!left_flanking || cmark_utf8proc_is_punctuation(after_char));
   } else if (c == '\'' || c == '"') {
-    *can_open = left_flanking && !right_flanking &&
-	         before_char != ']' && before_char != ')';
+    *can_open = left_flanking &&
+         (!right_flanking || before_char == '(' || before_char == '[') &&
+         before_char != ']' && before_char != ')';
     *can_close = right_flanking;
   } else {
     *can_open = left_flanking;
@@ -1118,7 +1119,7 @@ static bufsize_t manual_scan_link_url_2(cmark_chunk *input, bufsize_t offset,
     }
   }
 
-  if (i >= input->len)
+  if (i >= input->len || nb_p != 0)
     return -1;
 
   {
diff --git a/test/regression.txt b/test/regression.txt
index 0ec493d3d..25873629d 100644
--- a/test/regression.txt
+++ b/test/regression.txt
@@ -237,6 +237,18 @@ Issue commonmark#526 - unescaped ( in link title
 <p>[link](url ((title))</p>
 ````````````````````````````````
 
+Issue commonmark.js#177 - Unbalanced parentheses in link URLs should not be parsed as links
+
+```````````````````````````````` example
+[link](/u(ri )
+[link](/u(ri
+)
+.
+<p>[link](/u(ri )
+[link](/u(ri
+)</p>
+````````````````````````````````
+
 Issue commonamrk#517 - script, pre, style close tag without
 opener.