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CVE-2018-16844: nginx HTTP/2 may cause high CPU usage

CVE-2018-16844 · published 7 years ago

Summary

Versions of nginx earlier than 1.15.6 and 1.14.1 can consume excessive processor power when HTTP/2 is enabled. This only affects installations that have the HTTP/2 module turned on in the configuration. Update nginx to the latest version or disable the HTTP/2 option to prevent the problem.

What to do

Update apple xcode to version 13.0 or later.

Affected software

Vendor	Product	Affected versions
f5	nginx	>= 1.9.5, < 1.14.1 >= 1.15.0, < 1.15.6 `cpe:2.3:a:f5:nginx::::::::`
debian	debian_linux	9.0 `cpe:2.3:o:debian:debian_linux:9.0:::::::*`
canonical	ubuntu_linux	14.04 16.04 18.04 18.10 `cpe:2.3:o:canonical:ubuntu_linux:14.04::::lts:::`
apple	xcode	< 13.0 `cpe:2.3:a:apple:xcode::::::::`

Original advisory text

nginx before versions 1.15.6 and 1.14.1 has a vulnerability in the implementation of HTTP/2 that can allow for excessive CPU usage. This issue affects 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.

References

http://lists.opensuse.org/opensuse-security-announce/2019-09/msg00035.html Third Party Advisory
http://mailman.nginx.org/pipermail/nginx-announce/2018/000220.html Mailing List Vendor Advisory
http://seclists.org/fulldisclosure/2021/Sep/36 Mailing List Third Party Advisory
http://www.securityfocus.com/bid/105868 Third Party Advisory VDB Entry
http://www.securitytracker.com/id/1042038 Third Party Advisory VDB Entry
https://access.redhat.com/errata/RHSA-2018:3680 Third Party Advisory
https://access.redhat.com/errata/RHSA-2018:3681 Third Party Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2018-16844 Issue Tracking
https://support.apple.com/kb/HT212818 Third Party Advisory
https://usn.ubuntu.com/3812-1/ Third Party Advisory
https://www.debian.org/security/2018/dsa-4335 Third Party Advisory

Fix within

Internet-facing 14 days

Internal 60 days

Not known to be exploited
Can be exploited automatically (estimated)
Gives an attacker partial control (estimated)

Severity

7.5 High

Exploitation

13% chance of attack within 30 days

Type

CWE-400Uncontrolled Resource Consumption

Timeline

Published7 Nov 2018

Updated11 Oct 2026

First seen29 Sep 2026

Sources

CVE-2018-16844 · NVD

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