diff -u -r a/src/http/ngx_http_request.c b/src/http/ngx_http_request.c
--- a/src/http/ngx_http_request.c	2019-04-23 15:12:58.000000000 +0200
+++ b/src/http/ngx_http_request.c	2019-08-07 12:45:34.535553808 +0200
@@ -766,6 +766,12 @@
 
             return;
         }
+        if (buf[0] == 0x15 /* SSLv3/TLSv1 alert */) {
+            ngx_log_error(NGX_LOG_INFO, c->log, 0, "peer sent SSL alert");
+            ngx_http_close_connection(c);
+
+            return;
+        }
 
         ngx_log_debug0(NGX_LOG_DEBUG_HTTP, rev->log, 0, "plain http");