From 76833b9e684f0f05931adabf400bf61d32692e31 Mon Sep 17 00:00:00 2001
From: Joe Cooper <swelljoe@gmail.com>
Date: Thu, 21 May 2026 23:32:14 -0500
Subject: [PATCH 1/4] Add some ui-lib tests and fix quote escapes

---
 t/ui-lib-escaping.t | 135 ++++++++++++++++++++++++++++++++++++++++++++
 ui-lib.pl           |  19 +++++--
 2 files changed, 149 insertions(+), 5 deletions(-)
 create mode 100644 t/ui-lib-escaping.t

diff --git a/t/ui-lib-escaping.t b/t/ui-lib-escaping.t
new file mode 100644
index 000000000..ffc441244
--- /dev/null
+++ b/t/ui-lib-escaping.t
@@ -0,0 +1,135 @@
+#!/usr/bin/perl
+# Tests for ui-lib.pl attribute escaping and XSS resistance.
+#
+# These cover the *default* (non-theme) code path. Each function checks for
+# a theme override first and returns early if one is defined; when ui-lib.pl
+# is loaded as a library, no theme is present, so the default path runs.
+#
+# The core invariant: caller-supplied data interpolated into HTML must not
+# escape its attribute context. We check this by stripping all quoted
+# attribute values from the output and asserting that no event-handler
+# attribute (on*=) survives. If the input broke out of an attribute, the
+# handler appears outside any quoted region and the assertion fails.
+
+use strict;
+use warnings;
+use Test::More;
+use File::Basename qw(dirname);
+use File::Spec;
+
+my $root = File::Spec->rel2abs(File::Spec->catfile(dirname(__FILE__), '..'));
+require File::Spec->catfile($root, 'web-lib-funcs.pl');
+require File::Spec->catfile($root, 'ui-lib.pl');
+
+# Strip all "..." and '...' quoted regions from $html so that what remains
+# is tag scaffolding only. Any attribute introduced by an attribute-quote
+# breakout will appear in the stripped output.
+sub strip_attr_values {
+	my ($html) = @_;
+	$html =~ s/"[^"]*"//g;
+	$html =~ s/'[^']*'//g;
+	return $html;
+}
+
+sub assert_no_handler_injection {
+	my ($html, $label) = @_;
+	my $bare = strip_attr_values($html);
+	unlike($bare, qr/\bon[a-z]+\s*=/i,
+		"$label: no event-handler attribute leaks out of attribute value");
+}
+
+# Attribute-breakout payloads. The first is for double-quoted attrs, the
+# second for single-quoted; we use whichever matches what the function
+# emits (or both, when uncertain).
+my $xss_dq = q{x"onmouseover="alert(1)};
+my $xss_sq = q{x' onmouseover='alert(1)};
+
+# ---- safe-contract regression tests ---------------------------------------
+# These functions already escape correctly today. The tests lock that down.
+
+assert_no_handler_injection(main::ui_textbox('field', $xss_dq, 20),
+	'ui_textbox value');
+assert_no_handler_injection(main::ui_textbox($xss_dq, 'safe', 20),
+	'ui_textbox name');
+
+# ui_textarea must escape < so a value cannot inject </textarea>.
+{
+	my $payload = q{</textarea><script>alert(1)</script>};
+	my $html = main::ui_textarea('field', $payload, 5, 40);
+	unlike($html, qr{</textarea><script}i,
+		'ui_textarea value cannot close the textarea');
+	like($html, qr{&lt;/textarea}, 'ui_textarea value html-escapes <');
+}
+
+assert_no_handler_injection(main::ui_hidden($xss_dq, $xss_dq),
+	'ui_hidden name+value');
+assert_no_handler_injection(
+	main::ui_select('field', '', [[$xss_dq, 'label']]),
+	'ui_select option value');
+assert_no_handler_injection(main::ui_select($xss_dq, '', [['v','label']]),
+	'ui_select name');
+assert_no_handler_injection(main::ui_checkbox($xss_dq, 'v', 'label', 0),
+	'ui_checkbox name');
+assert_no_handler_injection(main::ui_oneradio($xss_dq, 'v', 'label', 0),
+	'ui_oneradio name');
+assert_no_handler_injection(main::ui_password('field', $xss_dq, 20),
+	'ui_password value');
+assert_no_handler_injection(main::ui_submit($xss_dq),
+	'ui_submit label');
+assert_no_handler_injection(main::ui_button($xss_dq),
+	'ui_button label');
+
+# ui_tag_start --- attribute values go through quote_escape.
+assert_no_handler_injection(
+	main::ui_tag_start('div', { 'data-foo' => $xss_dq }),
+	'ui_tag_start data attribute');
+
+# ---- the three XSS sites we are about to fix ------------------------------
+
+# ui_help: title goes into aria-label="...". Single-quote breakout doesn't
+# apply (attr is double-quoted), but double-quote breakout does.
+assert_no_handler_injection(main::ui_help($xss_dq),
+	'ui_help title');
+
+# ui_img: src/alt/title all in single-quoted attrs today.
+assert_no_handler_injection(main::ui_img('img.png', $xss_sq),
+	'ui_img alt');
+assert_no_handler_injection(main::ui_img('img.png', 'safe', $xss_sq),
+	'ui_img title');
+assert_no_handler_injection(
+	main::ui_img(q{img.png' onerror='alert(1)}, 'safe'),
+	'ui_img src');
+
+# js_redirect: url must not be able to close the script tag, and the
+# timeout/window parameters must not allow JS injection.
+{
+	# A literal </script> in script data closes the script element.
+	# An extra <script> in script data is just text — the parser is
+	# already in script-data state and only </script> exits it. So we
+	# only assert on the close-tag count.
+	my $url = q{/foo</script><script>alert(1)//};
+	my $html = main::js_redirect($url);
+	my $closes = () = $html =~ m{</script>}gi;
+	is($closes, 1, 'js_redirect: url cannot inject </script>');
+}
+{
+	# <!-- transitions the parser into script-data-escaped state, where
+	# a subsequent <script>...</script> pair can hide the real closing
+	# tag. The URL escape must neutralise this too.
+	my $url = q{/foo<!--<script>alert(1)</script>-->};
+	my $html = main::js_redirect($url);
+	my $closes = () = $html =~ m{</script>}gi;
+	is($closes, 1, 'js_redirect: url cannot inject <!-- script-data-escape');
+}
+{
+	my $html = main::js_redirect('/x', undef, q{0);alert(1);//});
+	unlike($html, qr/alert\(1\)/,
+		'js_redirect: timeout coerced, no JS injection');
+}
+{
+	my $html = main::js_redirect('/x', q{window;alert(1);//});
+	unlike($html, qr/alert\(1\)/,
+		'js_redirect: window validated, no JS injection');
+}
+
+done_testing();
diff --git a/ui-lib.pl b/ui-lib.pl
index e556f6759..676c422fc 100755
--- a/ui-lib.pl
+++ b/ui-lib.pl
@@ -59,7 +59,7 @@ sub ui_help
 {
 return &theme_ui_help(@_) if (defined(&theme_ui_help));
 my ($title) = @_;
-$title = html_strip($title);
+$title = &html_escape(&html_strip($title));
 return ("<sup class=\"ui_help\" aria-label=\"$title\" data-tooltip><samp>?</samp></sup>");
 }
 
@@ -83,7 +83,10 @@ sub ui_img
 {
 return &theme_ui_img(@_) if (defined(&theme_ui_img));
 my ($src, $alt, $title, $class, $tags) = @_;
-return ("<img src='".$src."' class='ui_img".($class ? " ".$class : "")."' alt='$alt' ".($title ? "title='$title'" : "").($tags ? " ".$tags : "").">");
+my $esrc   = &quote_escape($src);
+my $ealt   = &quote_escape($alt);
+my $etitle = &quote_escape($title);
+return ("<img src='".$esrc."' class='ui_img".($class ? " ".$class : "")."' alt='$ealt' ".($title ne '' ? "title='$etitle'" : "").($tags ? " ".$tags : "").">");
 }
 
 =head2 ui_link_button(href, text, [target], [tags])
@@ -2919,15 +2922,21 @@ my ($url, $window, $timeout) = @_;
 if (defined(&theme_js_redirect)) {
 	return &theme_js_redirect(@_);
 	}
-$window ||= "window";
-$timeout ||= 0;
+$window = $window && $window =~ /^[\w.]+$/ ? $window : "window";
+$timeout = int($timeout);
 if ($url =~ /^\//) {
 	# If the URL is like /foo , add webprefix
 	$url = &get_webprefix().$url;
 	}
+$url = &quote_escape($url);
+# Prevent the URL from terminating or destabilising the enclosing
+# script element. </script> would close it outright; <!-- would push
+# the parser into script-data-escaped state.
+$url =~ s|</script|<\\/script|gi;
+$url =~ s|<!--|<\\!--|g;
 return "<script type='text/javascript'>
 		setTimeout(function(){
-			${window}.location = '".&quote_escape($url)."';
+			${window}.location = '$url';
 		}, $timeout);
 	</script>";
 }

From 69548c4bb8e1c687b8c723e8e0f020966ea54b02 Mon Sep 17 00:00:00 2001
From: Joe Cooper <swelljoe@gmail.com>
Date: Mon, 15 Jun 2026 16:35:42 -0500
Subject: [PATCH 2/4] Escape in ui_select, too

---
 t/ui-lib-escaping.t | 24 ++++++++++++++++++++++++
 ui-lib.pl           |  4 ++--
 2 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/t/ui-lib-escaping.t b/t/ui-lib-escaping.t
index ffc441244..fd002715d 100644
--- a/t/ui-lib-escaping.t
+++ b/t/ui-lib-escaping.t
@@ -68,6 +68,30 @@ assert_no_handler_injection(
 	'ui_select option value');
 assert_no_handler_injection(main::ui_select($xss_dq, '', [['v','label']]),
 	'ui_select name');
+
+# ui_select option label is element content, not an attribute, so it must be
+# html-escaped to stop a label breaking out of the <option>/<select>.
+{
+	my $payload = q{</option></select><img src=x onerror=alert(1)>};
+	my $html = main::ui_select('field', '', [['v', $payload]]);
+	unlike($html, qr{</option></select><img}i,
+		'ui_select option label cannot close the option/select');
+	like($html, qr{&lt;/option}, 'ui_select option label html-escapes <');
+}
+# Single-element option: the value doubles as the label and must be escaped
+# in content position too.
+{
+	my $html = main::ui_select('field', '', [['<img src=x onerror=alert(1)>']]);
+	assert_no_handler_injection($html, 'ui_select fallback label');
+	like($html, qr{&lt;img}, 'ui_select fallback label html-escapes <');
+}
+# add-if-missing branch emits a selected value as its own label.
+{
+	my $html = main::ui_select('field', '<img src=x onerror=alert(1)>',
+				   [['other', 'Other']], 0, 0, 1);
+	assert_no_handler_injection($html, 'ui_select missing-value label');
+	like($html, qr{&lt;img}, 'ui_select missing-value label html-escapes <');
+}
 assert_no_handler_injection(main::ui_checkbox($xss_dq, 'v', 'label', 0),
 	'ui_checkbox name');
 assert_no_handler_injection(main::ui_oneradio($xss_dq, 'v', 'label', 0),
diff --git a/ui-lib.pl b/ui-lib.pl
index 676c422fc..309d24c28 100755
--- a/ui-lib.pl
+++ b/ui-lib.pl
@@ -1107,13 +1107,13 @@ foreach $o (@$opts) {
 	$o = [ $o ] if (!ref($o));
 	$rv .= "<option value=\"".&quote_escape($o->[0])."\"".
 	       ($sel{$o->[0]} ? " selected" : "").($o->[2] ne '' ? " ".$o->[2] : "").">".
-	       ($o->[1] || $o->[0])."</option>\n";
+	       &html_escape($o->[1] || $o->[0], 1)."</option>\n";
 	$opt{$o->[0]}++;
 	}
 foreach $s (keys %sel) {
 	if (!$opt{$s} && $missing) {
 		$rv .= "<option value=\"".&quote_escape($s)."\"".
-		       " selected>".($s eq "" ? "&nbsp;" : $s)."</option>\n";
+		       " selected>".($s eq "" ? "&nbsp;" : &html_escape($s, 1))."</option>\n";
 		}
 	}
 $rv .= "</select>\n";

From 25fea8f568ca475a10c69db32f0cd48f107c2eca Mon Sep 17 00:00:00 2001
From: Joe Cooper <swelljoe@gmail.com>
Date: Mon, 15 Jun 2026 16:38:34 -0500
Subject: [PATCH 3/4] Fix incorrect ui_select callers

---
 status/edit_mon.cgi    | 2 +-
 syslog-ng/edit_log.cgi | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/status/edit_mon.cgi b/status/edit_mon.cgi
index 69416c082..cbc190027 100755
--- a/status/edit_mon.cgi
+++ b/status/edit_mon.cgi
@@ -214,7 +214,7 @@ if (@servs) {
 	  &ui_select("depend", $serv->{'depend'},
 		 [ [ "", "&nbsp;" ],
 		   map { [ $_->{'id'}, $_->{'desc'}.
-				       " (".&nice_remotes($_).")" ] }
+				       " (".&html_strip(&nice_remotes($_), " ").")" ] }
 		     sort { $a->{'desc'} cmp $b->{'desc'} } @servs ]),
 	  undef, \@tds);
 	}
diff --git a/syslog-ng/edit_log.cgi b/syslog-ng/edit_log.cgi
index 9b642a5e8..963a75f11 100755
--- a/syslog-ng/edit_log.cgi
+++ b/syslog-ng/edit_log.cgi
@@ -53,7 +53,7 @@ print &ui_table_row($text{'log_filter'},
     &ui_select("filter", \@gotfilters, \@allfilters, 10, 1));
 
 # Show destinations
-@alldestinations = map { [ $_->{'value'}, $_->{'value'}." (".&nice_destination_file($_).")" ] } &find("destination", $conf);
+@alldestinations = map { [ $_->{'value'}, $_->{'value'}." (".&html_strip(&nice_destination_file($_)).")" ] } &find("destination", $conf);
 @gotdestinations = map { $_->{'value'} } &find("destination",$log->{'members'});
 print &ui_table_row($text{'log_destination'},
     &ui_select("destination", \@gotdestinations, \@alldestinations, 10, 1));

From b97756b9fb2b7518c479607ce6fe3da3e1429544 Mon Sep 17 00:00:00 2001
From: Joe Cooper <swelljoe@gmail.com>
Date: Mon, 15 Jun 2026 22:49:27 -0500
Subject: [PATCH 4/4] Escape every <

---
 ui-lib.pl | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/ui-lib.pl b/ui-lib.pl
index 309d24c28..3bc9a50f0 100755
--- a/ui-lib.pl
+++ b/ui-lib.pl
@@ -2930,10 +2930,11 @@ if ($url =~ /^\//) {
 	}
 $url = &quote_escape($url);
 # Prevent the URL from terminating or destabilising the enclosing
-# script element. </script> would close it outright; <!-- would push
-# the parser into script-data-escaped state.
-$url =~ s|</script|<\\/script|gi;
-$url =~ s|<!--|<\\!--|g;
+# script element. Escaping every "<" stops the HTML parser from ever
+# seeing </script (which would close it) or <!-- (which would enter
+# script-data-escaped state). < evaluates back to "<" in JS, so
+# the redirect target is preserved.
+$url =~ s|<|\\u003C|g;
 return "<script type='text/javascript'>
 		setTimeout(function(){
 			${window}.location = '$url';