#VU22597 Inconsistent interpretation of HTTP requests in HAProxy - CVE-2019-18277

Vulnerability identifier: #VU22597

Vulnerability risk: Medium

CVSSv4.0: 2.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2019-18277

CWE-ID: CWE-444

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
HAProxy
Server applications / IDS/IPS systems, Firewalls and proxy servers

Vendor: HAProxy

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

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

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Q & A

Can this vulnerability be exploited remotely?

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

Is there known malware, which exploits this vulnerability?

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