CVE-2019-18277

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 v3.1

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

CVSS v2.0

4.3 MEDIUMAV:N/AC:M/Au:N/C:N/I:P/A:N

EPSS

10.02% chance of exploitation in the next 30 days, 95th percentile

Published

2019-10-23

Updated

2024-08-05

Proof-of-concept exploits (1)

• https://nathandavison.com/blog/haproxy-http-request-smuggling

References

• CVE Record
• NVD entry

Related

• CVE-2019-18276
• CVE-2019-18278
• CVE-2019-18217
• CVE-2019-18292
• CVE-2019-18213
• CVE-2019-18304