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<title>[60649] trunk: HTML API: Improve script tag escape state processing.</title>
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<dt style="float: left; width: 6em; font-weight: bold">Revision</dt> <dd><a style="font-weight: bold" href="https://core.trac.wordpress.org/changeset/60649">60649</a><script type="application/ld+json">{"@context":"http://schema.org","@type":"EmailMessage","description":"Review this Commit","action":{"@type":"ViewAction","url":"https://core.trac.wordpress.org/changeset/60649","name":"Review Commit"}}</script></dd>
<dt style="float: left; width: 6em; font-weight: bold">Author</dt> <dd>jonsurrell</dd>
<dt style="float: left; width: 6em; font-weight: bold">Date</dt> <dd>2025-08-19 19:07:11 +0000 (Tue, 19 Aug 2025)</dd>
</dl>
<pre style='padding-left: 1em; margin: 2em 0; border-left: 2px solid #ccc; line-height: 1.25; font-size: 105%; font-family: sans-serif'>HTML API: Improve script tag escape state processing.
Addresses some edge cases parsing of script tag contents:
- "<!-->" remains in the unescaped state and does not enter the escaped state.
- Contents in the escaped state that end with "<script" do not enter double-escaped state.
- "\f" (Form Feed) was missing as a tag name terminating character.
Developed in https://github.com/WordPress/wordpress-develop/pull/9397 and https://github.com/WordPress/wordpress-develop/pull/9402.
Props jonsurrell, dmsnell.
See <a href="https://core.trac.wordpress.org/ticket/63738">#63738</a>.</pre>
<h3>Modified Paths</h3>
<ul>
<li><a href="#trunksrcwpincludeshtmlapiclasswphtmltagprocessorphp">trunk/src/wp-includes/html-api/class-wp-html-tag-processor.php</a></li>
<li><a href="#trunktestsphpunittestshtmlapiwpHtmlTagProcessorphp">trunk/tests/phpunit/tests/html-api/wpHtmlTagProcessor.php</a></li>
</ul>
</div>
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<h3>Diff</h3>
<a id="trunksrcwpincludeshtmlapiclasswphtmltagprocessorphp"></a>
<div class="modfile"><h4 style="background-color: #eee; color: inherit; margin: 1em 0; padding: 1.3em; font-size: 115%">Modified: trunk/src/wp-includes/html-api/class-wp-html-tag-processor.php</h4>
<pre class="diff"><span>
<span class="info" style="display: block; padding: 0 10px; color: #888">--- trunk/src/wp-includes/html-api/class-wp-html-tag-processor.php 2025-08-19 18:50:05 UTC (rev 60648)
+++ trunk/src/wp-includes/html-api/class-wp-html-tag-processor.php 2025-08-19 19:07:11 UTC (rev 60649)
</span><span class="lines" style="display: block; padding: 0 10px; color: #888">@@ -1556,24 +1556,33 @@
</span><span class="cx" style="display: block; padding: 0 10px"> }
</span><span class="cx" style="display: block; padding: 0 10px">
</span><span class="cx" style="display: block; padding: 0 10px"> /*
</span><del style="background-color: #fdd; text-decoration:none; display:block; padding: 0 10px">- * Unlike with "-->", the "<!--" only transitions
- * into the escaped mode if not already there.
- *
- * Inside the escaped modes it will be ignored; and
- * should never break out of the double-escaped
- * mode and back into the escaped mode.
- *
- * While this requires a mode change, it does not
- * impact the parsing otherwise, so continue
- * parsing after updating the state.
</del><ins style="background-color: #dfd; text-decoration:none; display:block; padding: 0 10px">+ * "<!--" only transitions from _unescaped_ to _escaped_. This byte sequence is only
+ * significant in the _unescaped_ state and is ignored in any other state.
</ins><span class="cx" style="display: block; padding: 0 10px"> */
</span><span class="cx" style="display: block; padding: 0 10px"> if (
</span><ins style="background-color: #dfd; text-decoration:none; display:block; padding: 0 10px">+ 'unescaped' === $state &&
</ins><span class="cx" style="display: block; padding: 0 10px"> '!' === $html[ $at ] &&
</span><span class="cx" style="display: block; padding: 0 10px"> '-' === $html[ $at + 1 ] &&
</span><span class="cx" style="display: block; padding: 0 10px"> '-' === $html[ $at + 2 ]
</span><span class="cx" style="display: block; padding: 0 10px"> ) {
</span><del style="background-color: #fdd; text-decoration:none; display:block; padding: 0 10px">- $at += 3;
- $state = 'unescaped' === $state ? 'escaped' : $state;
</del><ins style="background-color: #dfd; text-decoration:none; display:block; padding: 0 10px">+ $at += 3;
+
+ /*
+ * The parser is ready to enter the _escaped_ state, but may remain in the
+ * _unescaped_ state. This occurs when "<!--" is immediately followed by a
+ * sequence of 0 or more "-" followed by ">". This is similar to abruptly closed
+ * HTML comments like "<!-->" or "<!--->".
+ *
+ * Note that this check may advance the position significantly and requires a
+ * length check to prevent bad offsets on inputs like `<script><!---------`.
+ */
+ $at += strspn( $html, '-', $at );
+ if ( $at < $doc_length && '>' === $html[ $at ] ) {
+ ++$at;
+ continue;
+ }
+
+ $state = 'escaped';
</ins><span class="cx" style="display: block; padding: 0 10px"> continue;
</span><span class="cx" style="display: block; padding: 0 10px"> }
</span><span class="cx" style="display: block; padding: 0 10px">
</span><span class="lines" style="display: block; padding: 0 10px; color: #888">@@ -1610,8 +1619,30 @@
</span><span class="cx" style="display: block; padding: 0 10px"> */
</span><span class="cx" style="display: block; padding: 0 10px"> $at += 6;
</span><span class="cx" style="display: block; padding: 0 10px"> $c = $html[ $at ];
</span><del style="background-color: #fdd; text-decoration:none; display:block; padding: 0 10px">- if ( ' ' !== $c && "\t" !== $c && "\r" !== $c && "\n" !== $c && '/' !== $c && '>' !== $c ) {
- ++$at;
</del><ins style="background-color: #dfd; text-decoration:none; display:block; padding: 0 10px">+ if (
+ /**
+ * These characters trigger state transitions of interest:
+ *
+ * - @see {https://html.spec.whatwg.org/multipage/parsing.html#script-data-end-tag-name-state}
+ * - @see {https://html.spec.whatwg.org/multipage/parsing.html#script-data-escaped-end-tag-name-state}
+ * - @see {https://html.spec.whatwg.org/multipage/parsing.html#script-data-double-escape-start-state}
+ * - @see {https://html.spec.whatwg.org/multipage/parsing.html#script-data-double-escape-end-state}
+ *
+ * The "\r" character is not present in the above references. However, "\r" must be
+ * treated the same as "\n". This is because the HTML Standard requires newline
+ * normalization during preprocessing which applies this replacement.
+ *
+ * - @see https://html.spec.whatwg.org/multipage/parsing.html#preprocessing-the-input-stream
+ * - @see https://infra.spec.whatwg.org/#normalize-newlines
+ */
+ '>' !== $c &&
+ ' ' !== $c &&
+ "\n" !== $c &&
+ '/' !== $c &&
+ "\t" !== $c &&
+ "\f" !== $c &&
+ "\r" !== $c
+ ) {
</ins><span class="cx" style="display: block; padding: 0 10px"> continue;
</span><span class="cx" style="display: block; padding: 0 10px"> }
</span><span class="cx" style="display: block; padding: 0 10px">
</span></span></pre></div>
<a id="trunktestsphpunittestshtmlapiwpHtmlTagProcessorphp"></a>
<div class="modfile"><h4 style="background-color: #eee; color: inherit; margin: 1em 0; padding: 1.3em; font-size: 115%">Modified: trunk/tests/phpunit/tests/html-api/wpHtmlTagProcessor.php</h4>
<pre class="diff"><span>
<span class="info" style="display: block; padding: 0 10px; color: #888">--- trunk/tests/phpunit/tests/html-api/wpHtmlTagProcessor.php 2025-08-19 18:50:05 UTC (rev 60648)
+++ trunk/tests/phpunit/tests/html-api/wpHtmlTagProcessor.php 2025-08-19 19:07:11 UTC (rev 60649)
</span><span class="lines" style="display: block; padding: 0 10px; color: #888">@@ -2009,19 +2009,51 @@
</span><span class="cx" style="display: block; padding: 0 10px"> /**
</span><span class="cx" style="display: block; padding: 0 10px"> * Data provider.
</span><span class="cx" style="display: block; padding: 0 10px"> */
</span><del style="background-color: #fdd; text-decoration:none; display:block; padding: 0 10px">- public static function data_script_tag(): array {
- return array(
- 'Basic script tag' => array( '<script></script>', true ),
- 'Script with type attribute' => array( '<script type="text/javascript"></script>', true ),
- 'Script data escaped' => array( '<script><!--</script>', true ),
- 'Script data double-escaped exit (comment)' => array( '<script><!--<script>--></script>', true ),
- 'Script data double-escaped exit (closed)' => array( '<script><!--<script></script></script>', true ),
- 'Script data double-escaped exit (closed/truncated)' => array( '<script><!--<script></script </script>', true ),
- 'Script data no double-escape' => array( '<script><!-- --><script></script>', true ),
</del><ins style="background-color: #dfd; text-decoration:none; display:block; padding: 0 10px">+ public static function data_script_tag(): Generator {
+ yield 'Basic script tag' => array( '<script></script>', true );
+ yield 'Script tag with </script> close' => array( '<script></script>', true );
+ yield 'Script tag with </script/> close' => array( '<script></script/>', true );
+ yield 'Script tag with </script > close' => array( '<script></script >', true );
+ yield 'Script tag with </script\n> close' => array( "<script></script\n>", true );
+ yield 'Script tag with </script\t> close' => array( "<script></script\t>", true );
+ yield 'Script tag with </script\f> close' => array( "<script></script\f>", true );
+ yield 'Script tag with </script\r> close' => array( "<script></script\r>", true );
+ yield 'Script with type attribute' => array( '<script type="text/javascript"></script>', true );
+ yield 'Script data escaped' => array( '<script><!--</script>', true );
+ yield 'Script data double-escaped exit (comment)' => array( '<script><!--<script>--></script>', true );
+ yield 'Script data double-escaped exit (closed ">")' => array( '<script><!--<script></script></script>', true );
+ yield 'Script data double-escaped exit (closed "/")' => array( '<script><!--<script></script/</script>', true );
+ yield 'Script data double-escaped exit (closed " ")' => array( '<script><!--<script></script </script>', true );
+ yield 'Script data double-escaped exit (closed "\n")' => array( "<script><!--<script></script\n</script>", true );
+ yield 'Script data double-escaped exit (closed "\t")' => array( "<script><!--<script></script\t</script>", true );
+ yield 'Script data double-escaped exit (closed "\f")' => array( "<script><!--<script></script\f</script>", true );
+ yield 'Script data double-escaped exit (closed "\r")' => array( "<script><!--<script></script\r</script>", true );
+ yield 'Script data no double-escape' => array( '<script><!-- --><script></script>', true );
+ yield 'Script data no double-escape (short comment)' => array( '<script><!--><script></script>', true );
+ yield 'Script data almost double-escaped' => array( '<script><!--<script</script>', true );
+ yield 'Script data with complex JavaScript' => array(
+ '<script>
+ var x = 10;
+ x--;
+ x < 0 ? x += 100 : x = (x + 1) - 1;
+ </script>',
+ true,
+ );
</ins><span class="cx" style="display: block; padding: 0 10px">
</span><del style="background-color: #fdd; text-decoration:none; display:block; padding: 0 10px">- 'Script tag with self-close flag (ignored)' => array( '<script />', false ),
- 'Script data double-escaped' => array( '<script><!--<script></script>', false ),
- );
</del><ins style="background-color: #dfd; text-decoration:none; display:block; padding: 0 10px">+ yield 'Script tag with self-close flag (ignored)' => array( '<script />', false );
+ yield 'Script data double-escaped' => array( '<script><!--<script></script>', false );
+ yield 'Unclosed script in escaped state' => array( '<script><!--------------', false );
+ yield 'Unclosed script in double escaped state' => array( '<script><!--<script ', false );
+ yield 'Document end in closer start' => array( '<script></', false );
+ yield 'Document end in script closer' => array( '<script></script', false );
+ yield 'Document end in script closer with attributes' => array( '<script></script attr="val"', false );
+ yield 'Script tag double-escaped with <script>' => array( '<script><!--<script></script>', false );
+ yield 'Script tag double-escaped with <script/' => array( '<script><!--<script/</script>', false );
+ yield 'Script tag double-escaped with <script ' => array( '<script><!--<script </script>', false );
+ yield 'Script tag double-escaped with <script\n' => array( "<script><!--<script\n</script>", false );
+ yield 'Script tag double-escaped with <script\t' => array( "<script><!--<script\t</script>", false );
+ yield 'Script tag double-escaped with <script\f' => array( "<script><!--<script\f</script>", false );
+ yield 'Script tag double-escaped with <script\r' => array( "<script><!--<script\r</script>", false );
</ins><span class="cx" style="display: block; padding: 0 10px"> }
</span><span class="cx" style="display: block; padding: 0 10px">
</span><span class="cx" style="display: block; padding: 0 10px"> /**
</span></span></pre>
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