CVE-2018-20615

A flaw was found in HAProxy, versions before 1.8.17 and 1.9.1. Mishandling occurs when a priority flag is set on too short HEADERS frame in the HTTP/2 decoder, allowing an out-of-bounds read and a subsequent crash to occur. A remote attacker can exploit this flaw to cause a denial of service. Those who do not use HTTP/2 are unaffected.

HTTP/2 support was added to haproxy in version 1.8, therefore OpenShift Container Platform (OCP) 3.7 and earlier are unaffected by this flaw, see [1]. OCP 3.11 added a configuration option to ose-haproxy-router that made enabling HTTP/2 support easy, [2]. Prior to that, in versions OCP 3.9 and 3.10, an administrator had to customize the haproxy router configuration to add HTTP/2 support, [3]. OCP 3.9, and 3.10 are rated as moderate because HTTP/2 support was not a standard configuration option, and therefore unlikely to be enabled.

Versions of haproxy included in Red Hat Enterprise Linux 6 and 7, excluding rh-haproxy18-haproxy in Red Hat Software Collections, are unaffected as they package versions of haproxy before 1.7.

[1] http://www.haproxy.org/news.html

[2] https://github.com/openshift/origin/pull/19968

[3] https://docs.openshift.com/container-platform/3.10/install_config/router/customized_haproxy_router.html

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

HTTP/2 support is disabled by default on OpenShift Container Platform 3.11. To mitigate this vulnerability keep it disabled. You can verify if HTTP/2 support is enabled by following the instructions in the upstream pull request, [1].

[1] https://github.com/openshift/origin/pull/19968