diff --git a/include/http1/http_parser.h b/include/http1/http_parser.h
index 466b047..6ed51dc 100644
--- a/include/http1/http_parser.h
+++ b/include/http1/http_parser.h
@@ -278,6 +278,7 @@ typedef struct http1_parser_t {
     uint16_t          cl_seen_count;         /* Number of Content-Length headers seen */
     uint16_t          header_count;          /* Number of header fields parsed (DoS cap) */
     uint16_t          host_seen_count;       /* Number of Host headers seen (RFC 9112 §3.2 — exactly one) */
+    uint16_t          ct_seen_count;          /* Number of Content-Type headers seen (RFC 9110 §8.3 — singleton) */
     bool              te_chunked_seen;       /* Transfer-Encoding: chunked seen */
 
     /* Boolean flags (clustered to avoid interior padding) */
diff --git a/src/http1/http_parser.c b/src/http1/http_parser.c
index d7861bb..e63b75c 100644
--- a/src/http1/http_parser.c
+++ b/src/http1/http_parser.c
@@ -224,6 +224,7 @@ static int on_message_begin(llhttp_t* llhttp_parser)
     parser->cl_seen_count = 0;
     parser->header_count = 0;
     parser->host_seen_count = 0;
+    parser->ct_seen_count = 0;
     parser->te_chunked_seen = false;
 
     return 0;
@@ -433,6 +434,15 @@ static void save_current_header(http1_parser_t *parser)
             parser->parse_error = HTTP_PARSE_ERR_INVALID_HOST;
             return;
         }
+    } else if (zend_string_equals_literal(name, "content-type")) {
+        /* RFC 9110 §8.3: Content-Type is a singleton. Two of them is
+         * ambiguous (which one frames the body?) — reject rather than
+         * comma-combine into a malformed media type. */
+        parser->ct_seen_count++;
+        if (UNEXPECTED(parser->ct_seen_count > 1)) {
+            parser->parse_error = HTTP_PARSE_ERR_MALFORMED;
+            return;
+        }
     } else if (zend_string_equals_literal(name, "connection")) {
         if (strncasecmp(ZSTR_VAL(value), "keep-alive", 10) == 0) {
             req->keep_alive = true;
@@ -572,6 +582,21 @@ static int on_headers_complete(llhttp_t* llhttp_parser)
         parser->uri_builder.s = NULL;  /* Transfer ownership */
     }
 
+    /* Reject a request-target carrying a raw fragment ('#', RFC 9112 §3.2 —
+     * fragments are never sent on the wire) or a backslash (not valid in a
+     * URI per RFC 3986; '\' vs '/' is parsed inconsistently and enables
+     * path-confusion). Percent-encoded forms (%23 / %5C) are untouched. */
+    if (req->uri != NULL) {
+        const char *u = ZSTR_VAL(req->uri);
+        const size_t ulen = ZSTR_LEN(req->uri);
+        for (size_t i = 0; i < ulen; i++) {
+            if (UNEXPECTED(u[i] == '#' || u[i] == '\\')) {
+                parser->parse_error = HTTP_PARSE_ERR_MALFORMED;
+                return -1;
+            }
+        }
+    }
+
     /* Get HTTP version */
     req->http_major = llhttp_parser->http_major;
     req->http_minor = llhttp_parser->http_minor;
diff --git a/tests/phpt/server/h1/021-request-target-hardening.phpt b/tests/phpt/server/h1/021-request-target-hardening.phpt
new file mode 100644
index 0000000..7793db3
--- /dev/null
+++ b/tests/phpt/server/h1/021-request-target-hardening.phpt
@@ -0,0 +1,78 @@
+--TEST--
+HttpServer: request-target + singleton-header hardening (fragment, backslash, dup Content-Type)
+--EXTENSIONS--
+true_async_server
+true_async
+--SKIPIF--
+<?php
+if (!function_exists('stream_socket_client')) die('skip sockets required');
+?>
+--FILE--
+<?php
+/* RFC hardening (issue #47, optional strictness):
+ *   - raw '#' in the request-target (a fragment, never sent on the wire,
+ *     RFC 9112 §3.2) → 400
+ *   - raw '\' in the request-target (not a URI char, RFC 3986; '\' vs '/'
+ *     is parsed inconsistently → path confusion) → 400
+ *   - duplicate Content-Type (RFC 9110 §8.3 singleton) → 400
+ * Percent-encoded %23 / %5C are legal and must still pass. */
+
+use TrueAsync\HttpServer;
+use TrueAsync\HttpServerConfig;
+use function Async\spawn;
+use function Async\await;
+
+$port = 19826 + getmypid() % 1000;
+$server = new HttpServer((new HttpServerConfig())
+    ->addListener('127.0.0.1', $port)->setReadTimeout(5)->setWriteTimeout(5));
+$server->addHttpHandler(function ($req, $res) {
+    $res->setStatusCode(200)->setBody('ok');
+});
+
+function probe(int $port, string $raw): int {
+    $fp = false;
+    for ($t = 0; $t < 20 && $fp === false; $t++) {
+        $fp = @stream_socket_client("tcp://127.0.0.1:$port", $e, $es, 2);
+        if ($fp === false) { usleep(10000); }
+    }
+    if ($fp === false) { return -1; }
+    fwrite($fp, $raw);
+    stream_set_timeout($fp, 2);
+    $r = '';
+    while (!feof($fp)) {
+        $c = fread($fp, 4096);
+        if ($c === '' || $c === false) break;
+        $r .= $c;
+        if (str_contains($r, "\r\n")) break;
+    }
+    fclose($fp);
+    return preg_match('#^HTTP/1\.[01] (\d{3})#', $r, $m) ? (int)$m[1] : 0;
+}
+
+$client = spawn(function () use ($port, $server) {
+    usleep(20000);
+    $h = "Host: a.com\r\nConnection: close\r\n\r\n";
+    echo "fragment=",   probe($port, "GET /p#frag HTTP/1.1\r\n$h"), "\n";
+    echo "backslash=",  probe($port, "GET /a\\b HTTP/1.1\r\n$h"), "\n";
+    echo "dup_ct=",      probe($port,
+        "POST / HTTP/1.1\r\nHost: a.com\r\nContent-Type: text/a\r\n"
+        . "Content-Type: text/b\r\nContent-Length: 0\r\nConnection: close\r\n\r\n"), "\n";
+    echo "encoded_hash=", probe($port, "GET /p%23frag HTTP/1.1\r\n$h"), "\n";
+    echo "normal=",       probe($port, "GET /ok?x=1 HTTP/1.1\r\n$h"), "\n";
+    echo "single_ct=",    probe($port,
+        "POST / HTTP/1.1\r\nHost: a.com\r\nContent-Type: text/a\r\n"
+        . "Content-Length: 0\r\nConnection: close\r\n\r\n"), "\n";
+    $server->stop();
+});
+
+$server->start();
+await($client);
+echo "done\n";
+--EXPECT--
+fragment=400
+backslash=400
+dup_ct=400
+encoded_hash=200
+normal=200
+single_ct=200
+done