diff --git a/patch/1.21.4/nginx-http2_per_iteration_stream_handling_limit.patch b/patch/1.21.4/nginx-http2_per_iteration_stream_handling_limit.patch
new file mode 100644
index 0000000..8451182
--- /dev/null
+++ b/patch/1.21.4/nginx-http2_per_iteration_stream_handling_limit.patch
@@ -0,0 +1,53 @@
+diff --git src/http/v2/ngx_http_v2.c src/http/v2/ngx_http_v2.c
+index 3afa8b638..228b060bf 100644
+--- src/http/v2/ngx_http_v2.c
++++ src/http/v2/ngx_http_v2.c
+@@ -361,6 +361,7 @@ ngx_http_v2_read_handler(ngx_event_t *rev)
+     ngx_log_debug0(NGX_LOG_DEBUG_HTTP, c->log, 0, "http2 read handler");
+
+     h2c->blocked = 1;
++    h2c->new_streams = 0;
+
+     if (c->close) {
+         c->close = 0;
+@@ -1321,6 +1322,14 @@ ngx_http_v2_state_headers(ngx_http_v2_connection_t *h2c, u_char *pos,
+         goto rst_stream;
+     }
+
++    if (h2c->new_streams++ >= 2 * h2scf->concurrent_streams) {
++        ngx_log_error(NGX_LOG_INFO, h2c->connection->log, 0,
++                      "client sent too many streams at once");
++
++        status = NGX_HTTP_V2_REFUSED_STREAM;
++        goto rst_stream;
++    }
++
+     if (!h2c->settings_ack
+         && !(h2c->state.flags & NGX_HTTP_V2_END_STREAM_FLAG)
+         && h2scf->preread_size < NGX_HTTP_V2_DEFAULT_WINDOW)
+@@ -1386,6 +1395,12 @@ ngx_http_v2_state_headers(ngx_http_v2_connection_t *h2c, u_char *pos,
+
+ rst_stream:
+
++    if (h2c->refused_streams++ > ngx_max(h2scf->concurrent_streams, 100)) {
++        ngx_log_error(NGX_LOG_INFO, h2c->connection->log, 0,
++                      "client sent too many refused streams");
++        return ngx_http_v2_connection_error(h2c, NGX_HTTP_V2_NO_ERROR);
++    }
++
+     if (ngx_http_v2_send_rst_stream(h2c, h2c->state.sid, status) != NGX_OK) {
+         return ngx_http_v2_connection_error(h2c, NGX_HTTP_V2_INTERNAL_ERROR);
+     }
+diff --git src/http/v2/ngx_http_v2.h src/http/v2/ngx_http_v2.h
+index 0eceae3d5..aef40bbb8 100644
+--- src/http/v2/ngx_http_v2.h
++++ src/http/v2/ngx_http_v2.h
+@@ -124,6 +124,8 @@ struct ngx_http_v2_connection_s {
+     ngx_uint_t                       processing;
+     ngx_uint_t                       frames;
+     ngx_uint_t                       idle;
++    ngx_uint_t                       new_streams;
++    ngx_uint_t                       refused_streams;
+     ngx_uint_t                       priority_limit;
+
+     ngx_uint_t                       pushing;