From 6e5347803ccb4606c043a41c77cd175aa9213ff3 Mon Sep 17 00:00:00 2001
From: Steven Johnstone <steven.james.johnstone@gmail.com>
Date: Wed, 19 Nov 2025 09:30:57 +0000
Subject: [PATCH] Prevent an infinite loop parsing a capture name

Fixes #3729.
---
 src/prism.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/prism.c b/src/prism.c
index 20037b5b9f..7059db8f1d 100644
--- a/src/prism.c
+++ b/src/prism.c
@@ -20395,6 +20395,9 @@ pm_named_capture_escape_unicode(pm_parser_t *parser, pm_buffer_t *unescaped, con
         }
 
         size_t length = pm_strspn_hexadecimal_digit(cursor, end - cursor);
+        if (length == 0) {
+            break;
+        }
         uint32_t value = escape_unicode(parser, cursor, length);
 
         (void) pm_buffer_append_unicode_codepoint(unescaped, value);