HTTP request smuggling in Nginx

1) Inconsistent interpretation of HTTP requests

EUVDB-ID: #VU24230

Risk: Medium

CVSSv4.0: 5.5 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:P/U:Green]

CVE-ID: CVE-2019-20372

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

Exploit availability: Yes

Description

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

The vulnerability exists with certain error_page configurations. A remote attacker can read unauthorized web pages in environments where NGINX is being fronted by a load balancer.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

nginx: 1.5.0 - 1.17.6

CPE2.3

• cpe:2.3:a:nginx:nginx:1.5.0:*:*:*:*:*:*:*
• cpe:2.3:a:nginx:nginx:1.5.1:*:*:*:*:*:*:*
• cpe:2.3:a:nginx:nginx:1.5.2:*:*:*:*:*:*:*
• cpe:2.3:a:nginx:nginx:1.5.3:*:*:*:*:*:*:*
• cpe:2.3:a:nginx:nginx:1.5.4:*:*:*:*:*:*:*
• cpe:2.3:a:nginx:nginx:1.5.5:*:*:*:*:*:*:*
• cpe:2.3:a:nginx:nginx:1.5.6:*:*:*:*:*:*:*
• cpe:2.3:a:nginx:nginx:1.5.7:*:*:*:*:*:*:*
• cpe:2.3:a:nginx:nginx:1.5.8:*:*:*:*:*:*:*
• cpe:2.3:a:nginx:nginx:1.5.9:*:*:*:*:*:*:*

External links

https://nginx.org/en/CHANGES
https://bertjwregeer.keybase.pub/2019-12-10%20-%20error_page%20request%20smuggling.pdf
https://duo.com/docs/dng-notes#version-1.5.4-january-2020
https://github.com/kubernetes/ingress-nginx/pull/4859
https://github.com/nginx/nginx/commit/c1be55f97211d38b69ac0c2027e6812ab8b1b94e

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.