diff --git a/sapi/fuzzer/Makefile.frag b/sapi/fuzzer/Makefile.frag
index c1fa75896912..eeae1eba8809 100644
--- a/sapi/fuzzer/Makefile.frag
+++ b/sapi/fuzzer/Makefile.frag
@@ -31,3 +31,6 @@ $(SAPI_FUZZER_PATH)/php-fuzz-mbstring: $(PHP_GLOBAL_OBJS) $(PHP_BINARY_OBJS) $(P
 
 $(SAPI_FUZZER_PATH)/php-fuzz-mbregex: $(PHP_GLOBAL_OBJS) $(PHP_BINARY_OBJS) $(PHP_FUZZER_MBREGEX_OBJS)
 	$(FUZZER_BUILD) $(PHP_FUZZER_MBREGEX_OBJS) -o $@
+
+$(SAPI_FUZZER_PATH)/php-fuzz-dom-html: $(PHP_GLOBAL_OBJS) $(PHP_BINARY_OBJS) $(PHP_FUZZER_DOM_HTML_OBJS)
+	$(FUZZER_BUILD) $(PHP_FUZZER_DOM_HTML_OBJS) -o $@
diff --git a/sapi/fuzzer/config.m4 b/sapi/fuzzer/config.m4
index ce045c8962d6..c4ef3b8f0653 100644
--- a/sapi/fuzzer/config.m4
+++ b/sapi/fuzzer/config.m4
@@ -70,5 +70,10 @@ if test "$PHP_FUZZER" != "no"; then
     fi
   fi
 
+  dnl HTML5 parsing of untrusted documents through the lexbor engine (ext/dom).
+  if test -n "$enable_dom" && test "$enable_dom" != "no"; then
+    PHP_FUZZER_TARGET([dom-html], [PHP_FUZZER_DOM_HTML_OBJS])
+  fi
+
   PHP_SUBST([PHP_FUZZER_BINARIES])
 fi
diff --git a/sapi/fuzzer/dict/dom-html b/sapi/fuzzer/dict/dom-html
new file mode 100644
index 000000000000..2bbb72733d98
--- /dev/null
+++ b/sapi/fuzzer/dict/dom-html
@@ -0,0 +1,58 @@
+# Tokens for HTML5 parsing (php-fuzz-dom-html).
+"<html"
+"</html"
+"<head"
+"</head"
+"<body"
+"</body"
+"<title"
+"<style"
+"<script"
+"<template"
+"<svg"
+"<math"
+"<foreignObject"
+"<table"
+"<tbody"
+"<tr"
+"<td"
+"<form"
+"<input"
+"<select"
+"<option"
+"<textarea"
+"<iframe"
+"<noscript"
+"<frameset"
+"<p"
+"<br/>"
+"<img"
+" src="
+" href="
+" rel="
+" type="
+" charset="
+" content="
+" name="
+" id="
+" class="
+" style="
+" xmlns="
+" xlink:href="
+"<!--"
+"-->"
+"<!DOCTYPE html>"
+"<![CDATA["
+"<!ENTITY"
+"<?php"
+"<?xml"
+"&amp;"
+"&lt;"
+"&#x41;"
+"&quot;"
+"&#0;"
+"meta charset=\""
+"http-equiv=\"Content-Type\""
+"base href=\""
+"srcset="
+" autofocus onfocus=alert(1)//"
diff --git a/sapi/fuzzer/fuzzer-dom-html.c b/sapi/fuzzer/fuzzer-dom-html.c
new file mode 100644
index 000000000000..e2cdfb3b478d
--- /dev/null
+++ b/sapi/fuzzer/fuzzer-dom-html.c
@@ -0,0 +1,85 @@
+/*
+   +----------------------------------------------------------------------+
+   | Copyright © The PHP Group and Contributors.                          |
+   | (drafted by the oss-fuzz-coverage-pipeline run 2026-11-09)           |
+   +----------------------------------------------------------------------+
+   | This source file is subject to the Modified BSD License that is      |
+   | bundled with this package in the file LICENSE, and is available      |
+   | through the World Wide Web at <https://www.php.net/license/>.        |
+   +----------------------------------------------------------------------+
+   | Authors: arthurscchan <github@arthurscchan>                          |
+   +----------------------------------------------------------------------+
+*/
+
+#include "fuzzer.h"
+
+#include "main/php.h"
+#include <main/php_config.h>
+#include "main/php_main.h"
+
+#include <stdio.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+#include "fuzzer-sapi.h"
+
+/* Large documents mostly slow down fuzzing without reaching new codepaths. */
+#define MAX_SIZE (1 * 1024 * 1024)
+
+/* createFromString()'s $options accept HTML_PARSE_* bits (LIBXML_NOERROR is
+ * 1<<5 = 32 in libxml2); 0 is the neutral default and HTML5 parsing is
+ * error-tolerant, so no suppression bit is needed. */
+#define FUZZER_HTML_OPTIONS 0
+
+int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size) {
+	if (Size > MAX_SIZE || Size < 2) {
+		return 0;
+	}
+
+	if (fuzzer_request_startup() == FAILURE) {
+		return 0;
+	}
+
+	fuzzer_setup_dummy_frame();
+
+	zend_string *class_name = zend_string_init(ZEND_STRL("Dom\\HTMLDocument"), 0);
+	zend_class_entry *ce = zend_lookup_class(class_name);
+	zend_string_release(class_name);
+
+	if (ce) {
+		/* Method table entries are stored lowercased; lookups are case-sensitive. */
+		zend_function *create = zend_hash_str_find_ptr(&ce->function_table, ZEND_STRL("createfromstring"));
+		zend_function *save = zend_hash_str_find_ptr(&ce->function_table, ZEND_STRL("savehtml"));
+		ZEND_ASSERT(create != NULL);
+		ZEND_ASSERT(save != NULL);
+
+		zval retval, args[3];
+		ZVAL_STRINGL(&args[0], (const char *) Data, Size);
+		ZVAL_LONG(&args[1], FUZZER_HTML_OPTIONS);
+		ZVAL_NULL(&args[2]);
+
+		/* Parse untrusted bytes into an HTML5 document (lexbor engine). */
+		zend_call_known_function(create, NULL, ce, &retval, 3, args, NULL);
+
+		/* Round-trip direction: serialize the parsed document back to HTML. */
+		if (Z_TYPE(retval) == IS_OBJECT && save != NULL) {
+			zval retval2;
+			zend_call_known_instance_method_with_0_params(save, Z_OBJ_P(&retval), &retval2);
+			zval_ptr_dtor(&retval2);
+		}
+		zval_ptr_dtor(&retval);
+		zval_ptr_dtor(&args[0]);
+
+		if (EG(exception)) {
+			zend_clear_exception();
+		}
+	}
+
+	fuzzer_request_shutdown();
+	return 0;
+}
+
+int LLVMFuzzerInitialize(int *argc, char ***argv) {
+	fuzzer_init_php(NULL);
+	return 0;
+}
diff --git a/sapi/fuzzer/generate_all.php b/sapi/fuzzer/generate_all.php
index 5794bdacc6ba..45eb9bc8fa7b 100644
--- a/sapi/fuzzer/generate_all.php
+++ b/sapi/fuzzer/generate_all.php
@@ -1,6 +1,7 @@
 <?php
 require __DIR__ . '/generate_unserialize_dict.php';
 require __DIR__ . '/generate_mbstring_dict.php';
+require __DIR__ . '/generate_domhtml_corpus.php';
 require __DIR__ . '/generate_unserializehash_corpus.php';
 require __DIR__ . '/generate_parser_corpus.php';
 
@@ -19,3 +20,7 @@
     __DIR__ . '/corpus/tracing-jit',
     ["$baseDir/Zend/tests", "$baseDir/ext/opcache/tests/jit"]
 );
+generate_domhtml_corpus(
+    __DIR__ . '/corpus/dom-html',
+    ["$baseDir/ext/dom/tests"]
+);
diff --git a/sapi/fuzzer/generate_domhtml_corpus.php b/sapi/fuzzer/generate_domhtml_corpus.php
new file mode 100644
index 000000000000..8d9deffdc3e4
--- /dev/null
+++ b/sapi/fuzzer/generate_domhtml_corpus.php
@@ -0,0 +1,39 @@
+<?php
+/* Assembles seeds for sapi/fuzzer/fuzzer-dom-html.c.
+ *
+ * The fuzzer feeds raw HTML bytes into Dom\HTMLDocument::createFromString() and
+ * serializes the result via saveHtml(). Seeds are the .html fixtures shipped with
+ * ext/dom tests, plus a few hand-built edge-case documents.
+ */
+function generate_domhtml_corpus(string $corpusDir, array $testDirs, int $maxLen = 512 * 1024) {
+    @mkdir($corpusDir, 0777, true);
+
+    $n = 0;
+    foreach ($testDirs as $testDir) {
+        if (!is_dir($testDir)) { continue; }
+        $it = new RecursiveIteratorIterator(new RecursiveDirectoryIterator($testDir));
+        foreach ($it as $file) {
+            if (!preg_match('/\.html$/i', (string) $file)) { continue; }
+            $content = file_get_contents((string) $file);
+            if ($content === false || $content === '' || strlen($content) > $maxLen) { continue; }
+            file_put_contents(sprintf('%s/domhtml_%03d.html', $corpusDir, $n++), $content);
+        }
+    }
+
+    /* Hand-built edge cases not present as fixtures. */
+    $extra = [
+        '<!DOCTYPE html><html><head><meta charset="windows-1252"><title>t</title></head>'
+            . '<body><p>caf&#233; &amp; &quot;quotes&quot; &#0;</p></body></html>',
+        '<body><svg><foreignObject><div xmlns="http://www.w3.org/1999/xhtml">x</div></foreignObject></svg>'
+            . '<math><mi>y</mi></math><template><tr><td>t</td></tr></template></body>',
+        '<table><tbody><tr><td><table><tr><td>deep</td></tr></table></td></tr></tbody></table>'
+            . '<p>unclosed <b>bold <i>both <span>spans',
+        '<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN"><html><!-- comment -- with -- dashes -->'
+            . '<head><script>if (1 < 2) { x = "</div>"; }</script><style>p:before { content: "</"; }</style></head></html>',
+        "\xEF\xBB\xBF<html><head><meta http-equiv=\"Content-Type\" content=\"text/html; charset=utf-8\">"
+            . '</head><body>' . str_repeat('<div class="x" data-y="1">d</div>', 8) . '</body></html>',
+    ];
+    foreach ($extra as $content) {
+        file_put_contents(sprintf('%s/domhtml_extra_%02d.html', $corpusDir, $n++), $content);
+    }
+}