id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc	uname	nginx_version
2472	Invalid request caused by '.' in the first URI component	Weitian LI		"Hi,

I found a request to `/% 2e% 2e/x` caused Nginx to response 400 with error:

{{{
2023/03/21 17:06:55 [info] 1552400#1552400: *6 client sent invalid request while reading client request line, client: 127.0.0.1, server: _, request: ""GET /% 2e% 2e/x HTTP/1.1""
}}}

Similarly, requests of `/% 2e% 2e`, `/.% 2e`, and `/% 2e.` all give the same 400 result.

However, requests of `/x/% 2e% 2e`, `/x/.% 2e`, and `/x/% 2e.` all work as expected.  Meanwhile, request of `/..` is also OK (so `..` and `% 2e% 2e` behave differently).

I traced the issue and found it was raised by [https://github.com/nginx/nginx/blame/master/src/http/ngx_http_parse.c#L1466], but I couldn't yet find the root cause.

N.B. please ignore the space between `%` and `2e`; otherwise, trac auto replace it with `.`. 

Thank you."	defect	closed	minor		nginx-core	1.22.x	invalid		Weitian LI	Linux xxx 6.1.6-arch1-3 #1 SMP PREEMPT_DYNAMIC Mon, 16 Jan 2023 12:51:23 +0000 x86_64 GNU/Linux	"nginx version: nginx/1.22.1
built with OpenSSL 3.0.7 1 Nov 2022
TLS SNI support enabled
configure arguments: --prefix=/etc/nginx --conf-path=/etc/nginx/nginx.conf --sbin-path=/usr/bin/nginx --pid-path=/run/nginx.pid --lock-path=/run/lock/nginx.lock --user=http --group=http --http-log-path=/var/log/nginx/access.log --error-log-path=stderr --http-client-body-temp-path=/var/lib/nginx/client-body --http-proxy-temp-path=/var/lib/nginx/proxy --http-fastcgi-temp-path=/var/lib/nginx/fastcgi --http-scgi-temp-path=/var/lib/nginx/scgi --http-uwsgi-temp-path=/var/lib/nginx/uwsgi --with-cc-opt='-march=x86-64 -mtune=generic -O2 -pipe -fno-plt -fexceptions -Wp,-D_FORTIFY_SOURCE=2 -Wformat -Werror=format-security -fstack-clash-protection -fcf-protection -flto=auto' --with-ld-opt='-Wl,-O1,--sort-common,--as-needed,-z,relro,-z,now -flto=auto' --with-compat --with-debug --with-file-aio --with-http_addition_module --with-http_auth_request_module --with-http_dav_module --with-http_degradation_module --with-http_flv_module --with-http_geoip_module --with-http_gunzip_module --with-http_gzip_static_module --with-http_mp4_module --with-http_realip_module --with-http_secure_link_module --with-http_slice_module --with-http_ssl_module --with-http_stub_status_module --with-http_sub_module --with-http_v2_module --with-mail --with-mail_ssl_module --with-pcre-jit --with-stream --with-stream_geoip_module --with-stream_realip_module --with-stream_ssl_module --with-stream_ssl_preread_module --with-threads"