ASA-2019-00519 – nginx: Excessive CPU usage in HTTP/2 with priority changes


Allele Security Alert

ASA-2019-00519

Identifier(s)

ASA-2019-00519, CVE-2019-9513

Title

Excessive CPU usage in HTTP/2 with priority changes

Vendor(s)

NGINX, Inc

Product(s)

nginx

Affected version(s)

nginx versions since 1.9.5 up to and including 1.17.2

Fixed version(s)

nginx version 1.17.3
nginx version 1.16.1

Proof of concept

Unknown

Description

Several security issues were identified in nginx HTTP/2 implementation, which might cause excessive memory consumption and CPU usage (CVE-2019-9511, CVE-2019-9513, CVE-2019-9516).

The issues affect nginx compiled with the ngx_http_v2_module (not compiled by default) if the “http2” option of the “listen” directive is used in a configuration file.

Technical details

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.

Credits

Jonathan Looney (Netflix)

Reference(s)

nginx security advisories
https://nginx.org/en/security_advisories.html

[nginx-announce] nginx security advisory (CVE-2019-9511, CVE-2019-9513, CVE-2019-9516)
https://mailman.nginx.org/pipermail/nginx-announce/2019/000249.html

HTTP/2 Denial of Service Advisory
https://github.com/Netflix/security-bulletins/blob/master/advisories/third-party/2019-002.md

NGINX Updates Mitigate the August 2019 HTTP/2 Vulnerabilities
https://www.nginx.com/blog/nginx-updates-mitigate-august-2019-http-2-vulnerabilities/

HTTP/2: limited number of PRIORITY frames.
https://hg.nginx.org/nginx/rev/45415228990b

Bug 1735741 (CVE-2019-9513) – CVE-2019-9513 HTTP/2: flood using PRIORITY frames resulting in excessive resource consumption
https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2019-9513

CVE-2019-9513 - Red Hat Customer Portal
https://access.redhat.com/security/cve/CVE-2019-9513

CVE-2019-9513
https://security-tracker.debian.org/tracker/CVE-2019-9513

CVE-2019-9513 in Ubuntu
https://people.canonical.com/~ubuntu-security/cve/CVE-2019-9513.html

CVE-2019-9513 | SUSE
https://www.suse.com/security/cve/CVE-2019-9513

CVE-2019-9513
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-9513

CVE-2019-9513
https://nvd.nist.gov/vuln/detail/CVE-2019-9513

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Last modified: August 25, 2019

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