HTTP request smuggling in lua-nginx-module for OpenResty

1) Inconsistent interpretation of HTTP requests

EUVDB-ID: #VU46107

Risk: Medium

CVSSv3.1: 6.3 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N/E:U/RL:O/RC:C]

CVE-ID: CVE-2020-11724

CWE-ID: CWE-444 - Inconsistent Interpretation of HTTP Requests ('HTTP Request Smuggling')

Exploit availability: No

Description

The vulnerability allows a remote attacker to preform HTTP request smuggling attacks.

The vulnerability exists due to improper validation of HTTP requests in ngx_http_lua_subrequest.c in lua-nginx-module for OpenResy. A remote attacker can send a specially crafted HTTP request to the server and smuggle arbitrary HTTP headers.

Successful exploitation of vulnerability may allow an attacker to poison HTTP cache and perform phishing attacks.

Mitigation

Install update from vendor's website.

Vulnerable software versions

OpenResty: 1.15.8.1 - 1.15.8.3

lua-nginx-module: 0.10.0 - 0.10.16 rc5

External links

http://github.com/openresty/lua-nginx-module/commit/9ab38e8ee35fc08a57636b1b6190dca70b0076fa
http://github.com/openresty/openresty/blob/4e8b4c395f842a078e429c80dd063b2323999957/patches/ngx_http_lua-0.10.15-fix_location_capture_content_length_chunked.patch
http://lists.debian.org/debian-lts-announce/2020/07/msg00014.html
http://www.debian.org/security/2020/dsa-4750

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

How the attacker can exploit this vulnerability?

The attacker would have to send a specially crafted request to the affected application in order to exploit this vulnerability.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.