{"id":"UBUNTU-CVE-2021-40438","details":"A crafted request uri-path can cause mod_proxy to forward the request to an origin server choosen by the remote user. This issue affects Apache HTTP Server 2.4.48 and earlier.","modified":"2026-04-22T14:56:56.076621Z","published":"2021-09-16T15:15:00Z","related":["USN-5090-1","USN-5090-2","USN-5090-2 (regression update esm)","USN-5090-3 (regression update)"],"upstream":["CVE-2021-40438"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2021-40438"},{"type":"REPORT","url":"https://httpd.apache.org/security/vulnerabilities_24.html#CVE-2021-40438"},{"type":"REPORT","url":"https://httpd.apache.org/security/vulnerabilities_24.html"},{"type":"ADVISORY","url":"https://ubuntu.com/security/notices/USN-5090-1"},{"type":"ADVISORY","url":"https://ubuntu.com/security/notices/USN-5090-2"},{"type":"ADVISORY","url":"https://ubuntu.com/security/notices/USN-5090-3"},{"type":"ADVISORY","url":"https://ubuntu.com/security/notices/USN-5090-2"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2021-40438"},{"type":"REPORT","url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog"}],"affected":[{"package":{"name":"apache2","ecosystem":"Ubuntu:Pro:16.04:LTS","purl":"pkg:deb/ubuntu/apache2@2.4.18-2ubuntu3.17+esm3?arch=source&distro=esm-infra/xenial"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.4.18-2ubuntu3.17+esm3"}]}],"versions":["2.4.12-2ubuntu2","2.4.17-1ubuntu1","2.4.17-2ubuntu1","2.4.17-3ubuntu1","2.4.18-1ubuntu1","2.4.18-2ubuntu1","2.4.18-2ubuntu2","2.4.18-2ubuntu3","2.4.18-2ubuntu3.1","2.4.18-2ubuntu3.2","2.4.18-2ubuntu3.3","2.4.18-2ubuntu3.4","2.4.18-2ubuntu3.5","2.4.18-2ubuntu3.7","2.4.18-2ubuntu3.8","2.4.18-2ubuntu3.9","2.4.18-2ubuntu3.10","2.4.18-2ubuntu3.12","2.4.18-2ubuntu3.13","2.4.18-2ubuntu3.14","2.4.18-2ubuntu3.15","2.4.18-2ubuntu3.17","2.4.18-2ubuntu3.17+esm1","2.4.18-2ubuntu3.17+esm2"],"ecosystem_specific":{"availability":"Available with Ubuntu Pro (Infra-only): https://ubuntu.com/pro","binaries":[{"binary_name":"apache2","binary_version":"2.4.18-2ubuntu3.17+esm3"},{"binary_name":"apache2-bin","binary_version":"2.4.18-2ubuntu3.17+esm3"},{"binary_name":"apache2-data","binary_version":"2.4.18-2ubuntu3.17+esm3"},{"binary_name":"apache2-suexec-custom","binary_version":"2.4.18-2ubuntu3.17+esm3"},{"binary_version":"2.4.18-2ubuntu3.17+esm3","binary_name":"apache2-suexec-pristine"},{"binary_name":"apache2-utils","binary_version":"2.4.18-2ubuntu3.17+esm3"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2021/UBUNTU-CVE-2021-40438.json"}},{"package":{"name":"apache2","ecosystem":"Ubuntu:18.04:LTS","purl":"pkg:deb/ubuntu/apache2@2.4.29-1ubuntu4.18?arch=source&distro=bionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.4.29-1ubuntu4.18"}]}],"versions":["2.4.27-2ubuntu3","2.4.29-1ubuntu1","2.4.29-1ubuntu2","2.4.29-1ubuntu3","2.4.29-1ubuntu4","2.4.29-1ubuntu4.1","2.4.29-1ubuntu4.2","2.4.29-1ubuntu4.3","2.4.29-1ubuntu4.4","2.4.29-1ubuntu4.5","2.4.29-1ubuntu4.6","2.4.29-1ubuntu4.7","2.4.29-1ubuntu4.8","2.4.29-1ubuntu4.10","2.4.29-1ubuntu4.11","2.4.29-1ubuntu4.12","2.4.29-1ubuntu4.13","2.4.29-1ubuntu4.14","2.4.29-1ubuntu4.16","2.4.29-1ubuntu4.17"],"ecosystem_specific":{"availability":"No subscription required","binaries":[{"binary_name":"apache2","binary_version":"2.4.29-1ubuntu4.18"},{"binary_name":"apache2-bin","binary_version":"2.4.29-1ubuntu4.18"},{"binary_name":"apache2-data","binary_version":"2.4.29-1ubuntu4.18"},{"binary_name":"apache2-suexec-custom","binary_version":"2.4.29-1ubuntu4.18"},{"binary_name":"apache2-suexec-pristine","binary_version":"2.4.29-1ubuntu4.18"},{"binary_version":"2.4.29-1ubuntu4.18","binary_name":"apache2-utils"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2021/UBUNTU-CVE-2021-40438.json"}},{"package":{"name":"apache2","ecosystem":"Ubuntu:20.04:LTS","purl":"pkg:deb/ubuntu/apache2@2.4.41-4ubuntu3.6?arch=source&distro=focal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.4.41-4ubuntu3.6"}]}],"versions":["2.4.41-1ubuntu1","2.4.41-4ubuntu1","2.4.41-4ubuntu2","2.4.41-4ubuntu3","2.4.41-4ubuntu3.1","2.4.41-4ubuntu3.3","2.4.41-4ubuntu3.4","2.4.41-4ubuntu3.5"],"ecosystem_specific":{"availability":"No subscription required","binaries":[{"binary_version":"2.4.41-4ubuntu3.6","binary_name":"apache2"},{"binary_name":"apache2-bin","binary_version":"2.4.41-4ubuntu3.6"},{"binary_name":"apache2-data","binary_version":"2.4.41-4ubuntu3.6"},{"binary_name":"apache2-suexec-custom","binary_version":"2.4.41-4ubuntu3.6"},{"binary_name":"apache2-suexec-pristine","binary_version":"2.4.41-4ubuntu3.6"},{"binary_name":"apache2-utils","binary_version":"2.4.41-4ubuntu3.6"},{"binary_name":"libapache2-mod-md","binary_version":"2.4.41-4ubuntu3.6"},{"binary_version":"2.4.41-4ubuntu3.6","binary_name":"libapache2-mod-proxy-uwsgi"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2021/UBUNTU-CVE-2021-40438.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H"},{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H"},{"type":"Ubuntu","score":"medium"}]}