Subject: [ASA-201908-13] nginx: denial of service

Arch Linux Security Advisory ASA-201908-13
==========================================

Severity: Medium
Date    : 2019-08-16
CVE-ID  : CVE-2019-9511 CVE-2019-9513 CVE-2019-9516
Package : nginx
Type    : denial of service
Remote  : Yes
Link    : https://security.archlinux.org/AVG-1023

Summary
=======

The package nginx before version 1.16.1-1 is vulnerable to denial of
service.

Resolution
==========

Upgrade to 1.16.1-1.

# pacman -Syu "nginx>=1.16.1-1"

The problems have been fixed upstream in version 1.16.1.

Workaround
==========

Disable http/2 support.

Description
===========

- CVE-2019-9511 (denial of service)

An issue has been found in several HTTP/2 implementations, where the
attacker requests a large amount of data from a specified resource over
multiple streams. They manipulate window size and stream priority to
force the server to queue the data in 1-byte chunks. Depending on how
efficiently this data is queued, this can consume excess CPU, memory,
or both, potentially leading to a denial of service.

- CVE-2019-9513 (denial of service)

An issue has been found in several HTTP/2 implementations, where the
attacker creates multiple request streams and continually shuffles the
priority of the streams in a way that causes substantial churn to the
priority tree. This can consume excess CPU, potentially leading to a
denial of service.

- CVE-2019-9516 (denial of service)

An issue has been found in several HTTP/2 implementations, where the
attacker sends a stream of headers with a 0-length header name and
0-length header value, optionally Huffman encoded into 1-byte or
greater headers. Some implementations allocate memory for these headers
and keep the allocation alive until the session dies. This can consume
excess memory, potentially leading to a denial of service.

Impact
======

A remote attacker is able cause a denial of service by sending a
specially crafted packet.

References
==========

https://mailman.nginx.org/pipermail/nginx-announce/2019/000249.html
https://github.com/Netflix/security-bulletins/blob/master/advisories/third-party/2019-002.md
https://github.com/nginx/nginx/commit/a987f81dd19210bc30b62591db331e31d3d74089
https://github.com/nginx/nginx/commit/5ae726912654da10a9a81b2c8436829f3e94f69f
https://github.com/nginx/nginx/commit/6dfbc8b1c2116f362bb871efebbf9df576738e89
https://security.archlinux.org/CVE-2019-9511
https://security.archlinux.org/CVE-2019-9513
https://security.archlinux.org/CVE-2019-9516