In Apache HTTP server versions 2.4.37 and prior, by sending request bodies in a slow loris way to plain resources, the h2 stream for that request unnecessarily occupied a server thread cleaning up that incoming data. This affects only HTTP/2 (mod_http2) connections.
The product does not properly control the allocation and maintenance of a limited resource.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Http_server | Apache | 2.4.17 (including) | 2.4.17 (including) |
| Http_server | Apache | 2.4.18 (including) | 2.4.18 (including) |
| Http_server | Apache | 2.4.20 (including) | 2.4.20 (including) |
| Http_server | Apache | 2.4.23 (including) | 2.4.23 (including) |
| Http_server | Apache | 2.4.25 (including) | 2.4.25 (including) |
| Http_server | Apache | 2.4.26 (including) | 2.4.26 (including) |
| Http_server | Apache | 2.4.27 (including) | 2.4.27 (including) |
| Http_server | Apache | 2.4.28 (including) | 2.4.28 (including) |
| Http_server | Apache | 2.4.29 (including) | 2.4.29 (including) |
| Http_server | Apache | 2.4.30 (including) | 2.4.30 (including) |
| Http_server | Apache | 2.4.33 (including) | 2.4.33 (including) |
| Http_server | Apache | 2.4.34 (including) | 2.4.34 (including) |
| Http_server | Apache | 2.4.35 (including) | 2.4.35 (including) |
| Http_server | Apache | 2.4.37 (including) | 2.4.37 (including) |
| JBoss Core Services on RHEL 6 | RedHat | jbcs-httpd24-apr-0:1.6.3-63.jbcs.el6 | * |
| JBoss Core Services on RHEL 6 | RedHat | jbcs-httpd24-apr-util-0:1.6.1-48.jbcs.el6 | * |
| JBoss Core Services on RHEL 6 | RedHat | jbcs-httpd24-brotli-0:1.0.6-7.jbcs.el6 | * |
| JBoss Core Services on RHEL 6 | RedHat | jbcs-httpd24-curl-0:7.64.1-14.jbcs.el6 | * |
| JBoss Core Services on RHEL 6 | RedHat | jbcs-httpd24-httpd-0:2.4.37-33.jbcs.el6 | * |
| JBoss Core Services on RHEL 6 | RedHat | jbcs-httpd24-jansson-0:2.11-20.jbcs.el6 | * |
| JBoss Core Services on RHEL 6 | RedHat | jbcs-httpd24-mod_cluster-native-0:1.3.12-9.Final_redhat_2.jbcs.el6 | * |
| JBoss Core Services on RHEL 6 | RedHat | jbcs-httpd24-mod_jk-0:1.2.46-22.redhat_1.jbcs.el6 | * |
| JBoss Core Services on RHEL 6 | RedHat | jbcs-httpd24-mod_security-0:2.9.2-16.GA.jbcs.el6 | * |
| JBoss Core Services on RHEL 6 | RedHat | jbcs-httpd24-nghttp2-0:1.39.2-4.jbcs.el6 | * |
| JBoss Core Services on RHEL 6 | RedHat | jbcs-httpd24-openssl-1:1.1.1-25.jbcs.el6 | * |
| JBoss Core Services on RHEL 7 | RedHat | jbcs-httpd24-apr-0:1.6.3-63.jbcs.el7 | * |
| JBoss Core Services on RHEL 7 | RedHat | jbcs-httpd24-apr-util-0:1.6.1-48.jbcs.el7 | * |
| JBoss Core Services on RHEL 7 | RedHat | jbcs-httpd24-brotli-0:1.0.6-7.jbcs.el7 | * |
| JBoss Core Services on RHEL 7 | RedHat | jbcs-httpd24-curl-0:7.64.1-14.jbcs.el7 | * |
| JBoss Core Services on RHEL 7 | RedHat | jbcs-httpd24-httpd-0:2.4.37-33.jbcs.el7 | * |
| JBoss Core Services on RHEL 7 | RedHat | jbcs-httpd24-jansson-0:2.11-20.jbcs.el7 | * |
| JBoss Core Services on RHEL 7 | RedHat | jbcs-httpd24-mod_cluster-native-0:1.3.12-9.Final_redhat_2.jbcs.el7 | * |
| JBoss Core Services on RHEL 7 | RedHat | jbcs-httpd24-mod_jk-0:1.2.46-22.redhat_1.jbcs.el7 | * |
| JBoss Core Services on RHEL 7 | RedHat | jbcs-httpd24-mod_security-0:2.9.2-16.GA.jbcs.el7 | * |
| JBoss Core Services on RHEL 7 | RedHat | jbcs-httpd24-nghttp2-0:1.39.2-4.jbcs.el7 | * |
| JBoss Core Services on RHEL 7 | RedHat | jbcs-httpd24-openssl-1:1.1.1-25.jbcs.el7 | * |
| Red Hat Enterprise Linux 8 | RedHat | httpd:2.4-8030020200818000036.30b713e6 | * |
| Red Hat Software Collections for Red Hat Enterprise Linux 6 | RedHat | httpd24-0:1.1-19.el6 | * |
| Red Hat Software Collections for Red Hat Enterprise Linux 6 | RedHat | httpd24-httpd-0:2.4.34-15.el6 | * |
| Red Hat Software Collections for Red Hat Enterprise Linux 6 | RedHat | httpd24-nghttp2-0:1.7.1-8.el6 | * |
| Red Hat Software Collections for Red Hat Enterprise Linux 7 | RedHat | httpd24-0:1.1-19.el7 | * |
| Red Hat Software Collections for Red Hat Enterprise Linux 7 | RedHat | httpd24-httpd-0:2.4.34-15.el7 | * |
| Red Hat Software Collections for Red Hat Enterprise Linux 7 | RedHat | httpd24-nghttp2-0:1.7.1-8.el7 | * |
| Red Hat Software Collections for Red Hat Enterprise Linux 7.5 EUS | RedHat | httpd24-0:1.1-19.el7 | * |
| Red Hat Software Collections for Red Hat Enterprise Linux 7.5 EUS | RedHat | httpd24-httpd-0:2.4.34-15.el7 | * |
| Red Hat Software Collections for Red Hat Enterprise Linux 7.5 EUS | RedHat | httpd24-nghttp2-0:1.7.1-8.el7 | * |
| Red Hat Software Collections for Red Hat Enterprise Linux 7.6 EUS | RedHat | httpd24-0:1.1-19.el7 | * |
| Red Hat Software Collections for Red Hat Enterprise Linux 7.6 EUS | RedHat | httpd24-httpd-0:2.4.34-15.el7 | * |
| Red Hat Software Collections for Red Hat Enterprise Linux 7.6 EUS | RedHat | httpd24-nghttp2-0:1.7.1-8.el7 | * |
| Red Hat Software Collections for Red Hat Enterprise Linux 7.7 EUS | RedHat | httpd24-0:1.1-19.el7 | * |
| Red Hat Software Collections for Red Hat Enterprise Linux 7.7 EUS | RedHat | httpd24-httpd-0:2.4.34-15.el7 | * |
| Red Hat Software Collections for Red Hat Enterprise Linux 7.7 EUS | RedHat | httpd24-nghttp2-0:1.7.1-8.el7 | * |
| Text-Only JBCS | RedHat | httpd | * |
| Apache2 | Ubuntu | bionic | * |
| Apache2 | Ubuntu | cosmic | * |
| Apache2 | Ubuntu | esm-infra/bionic | * |
| Apache2 | Ubuntu | upstream | * |
Mitigation of resource exhaustion attacks requires that the target system either:
The first of these solutions is an issue in itself though, since it may allow attackers to prevent the use of the system by a particular valid user. If the attacker impersonates the valid user, they may be able to prevent the user from accessing the server in question.
The second solution is simply difficult to effectively institute – and even when properly done, it does not provide a full solution. It simply makes the attack require more resources on the part of the attacker.