Allele Security Alert
Excessive CPU usage in HTTP/2 with priority changes
nginx versions since 1.9.5 up to and including 1.17.2
nginx version 1.17.3
nginx version 1.16.1
Proof of concept
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.
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.
Jonathan Looney (Netflix)
nginx security advisories
[nginx-announce] nginx security advisory (CVE-2019-9511, CVE-2019-9513, CVE-2019-9516)
HTTP/2 Denial of Service Advisory
NGINX Updates Mitigate the August 2019 HTTP/2 Vulnerabilities
HTTP/2: limited number of PRIORITY frames.
Bug 1735741 (CVE-2019-9513) – CVE-2019-9513 HTTP/2: flood using PRIORITY frames resulting in excessive resource consumption
CVE-2019-9513 - Red Hat Customer Portal
CVE-2019-9513 | SUSE
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Last modified: August 25, 2019