CVE-2019-18277 Information

Description

A flaw was found in HAProxy before 2.0.6. In legacy mode messages featuring a transfer-encoding header missing the \chunked\ value were not being correctly rejected. The impact was limited but if combined with the \http-reuse always\ setting it could be used to help construct an HTTP request smuggling attack against a vulnerable component employing a lenient parser that would ignore the content-length header as soon as it saw a transfer-encoding one (even if not entirely valid according to the specification).

CVSS Vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Reference

http://lists.opensuse.org/opensuse-security-announce/2019-12/msg00016.html http://lists.opensuse.org/opensuse-security-announce/2019-12/msg00019.html 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

Attack Complexity

LOW

Privileges Required

NONE

User Interaction Required

NONE

Scope

NONE

Confidentiality Impact

UNCHANGED

Integrity Impact

NONE

Availability Impact

HIGH

Base Score

NONE

Base Severity

7.5