HTTP request smuggling in HAProxy

1) Inconsistent interpretation of HTTP requests

EUVDB-ID: #VU22597

Risk: Medium

CVSSv3.1: 5.7 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N/E:U/RL:O/RC:C]

CVE-ID: CVE-2019-18277

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

Exploit availability: No

Description

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

The vulnerability exists due to incorrect processing of messages with a missing transfer-encoding header, when HAProxy is configured in legacy mode. The server does not reject "chunked" value that combined with the "http-reuse always" setting can lead to HTTP request smuggling attack.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

HAProxy: 2.0.0 - 2.0.5

External links

http://git.haproxy.org/?p=haproxy-2.0.git;a=commit;h=196a7df44d8129d1adc795da020b722614d6a581
http://nathandavison.com/blog/haproxy-http-request-smuggling
http://usn.ubuntu.com/4174-1/
http://www.mail-archive.com/haproxy@formilux.org/msg34926.html

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.