From e2a6fe571166160b9caed45f35910a7b9b50d2c0 Mon Sep 17 00:00:00 2001
From: Brian Wolff <bawolff+wn@gmail.com>
Date: Tue, 7 Jun 2016 22:35:15 -0400
Subject: [PATCH] SECURITY: XSS in unclosed internal links

rawurldecode was being run on unclosed internal links
which could allow an attacker to insert arbitrary
html into the page.

See also related: r13302

Bug: T137264
Change-Id: I4e112a9e918df9fe78b62c311939239b483a21f5
---
 includes/parser/Parser.php   | 2 +-
 tests/parser/parserTests.txt | 9 +++++++++
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/includes/parser/Parser.php b/includes/parser/Parser.php
index 4f579a93be..38eb621936 100644
--- a/includes/parser/Parser.php
+++ b/includes/parser/Parser.php
@@ -2158,7 +2158,7 @@ class Parser {
 				$might_be_img = true;
 				$text = $m[2];
 				if ( strpos( $m[1], '%' ) !== false ) {
-					$m[1] = rawurldecode( $m[1] );
+					$m[1] = str_replace( [ '<', '>' ], [ '&lt;', '&gt;' ], rawurldecode( $m[1] ) );
 				}
 				$trail = "";
 			} else { # Invalid form; output directly
diff --git a/tests/parser/parserTests.txt b/tests/parser/parserTests.txt
index d6d2b29976..c7bbc62356 100644
--- a/tests/parser/parserTests.txt
+++ b/tests/parser/parserTests.txt
@@ -27140,3 +27140,12 @@ Thumbnail output
 </div>
 </div>
 !! end
+
+!! test
+unclosed internal link XSS (T137264)
+!! wikitext
+[[#%3Cscript%3Ealert(1)%3C/script%3E|
+!! html
+<p>[[#&lt;script&gt;alert(1)&lt;/script&gt;|
+</p>
+!! end
-- 
2.20.1