{"id":"UBUNTU-CVE-2021-32066","details":"An issue was discovered in Ruby through 2.6.7, 2.7.x through 2.7.3, and 3.x through 3.0.1. Net::IMAP does not raise an exception when StartTLS fails with an an unknown response, which might allow man-in-the-middle attackers to bypass the TLS protections by leveraging a network position between the client and the registry to block the StartTLS command, aka a \"StartTLS stripping attack.\"","modified":"2026-04-22T14:45:07.544226Z","published":"2021-07-15T00:00:00Z","related":["USN-5020-1"],"upstream":["CVE-2021-32066"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2021-32066"},{"type":"REPORT","url":"https://www.ruby-lang.org/en/news/2021/07/07/starttls-stripping-in-net-imap/"},{"type":"REPORT","url":"https://github.com/ruby/ruby/commit/a21a3b7d23704a01d34bd79d09dc37897e00922a"},{"type":"ADVISORY","url":"https://ubuntu.com/security/notices/USN-5020-1"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2021-32066"}],"affected":[{"package":{"name":"ruby2.3","ecosystem":"Ubuntu:Pro:16.04:LTS","purl":"pkg:deb/ubuntu/ruby2.3@2.3.1-2~ubuntu16.04.16+esm1?arch=source&distro=esm-infra/xenial"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.3.1-2~ubuntu16.04.16+esm1"}]}],"versions":["2.3.0-1","2.3.0-2","2.3.0-4ubuntu2","2.3.0-4ubuntu3","2.3.0-5ubuntu1","2.3.1-2~16.04","2.3.1-2~16.04.2","2.3.1-2~16.04.4","2.3.1-2~16.04.5","2.3.1-2~16.04.6","2.3.1-2~16.04.7","2.3.1-2~16.04.9","2.3.1-2~16.04.10","2.3.1-2~16.04.11","2.3.1-2~16.04.12","2.3.1-2~ubuntu16.04.13","2.3.1-2~ubuntu16.04.14","2.3.1-2~ubuntu16.04.15","2.3.1-2~ubuntu16.04.16"],"ecosystem_specific":{"availability":"Available with Ubuntu Pro (Infra-only): https://ubuntu.com/pro","binaries":[{"binary_name":"libruby2.3","binary_version":"2.3.1-2~ubuntu16.04.16+esm1"},{"binary_name":"ruby2.3","binary_version":"2.3.1-2~ubuntu16.04.16+esm1"},{"binary_name":"ruby2.3-tcltk","binary_version":"2.3.1-2~ubuntu16.04.16+esm1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2021/UBUNTU-CVE-2021-32066.json"}},{"package":{"name":"ruby2.5","ecosystem":"Ubuntu:18.04:LTS","purl":"pkg:deb/ubuntu/ruby2.5@2.5.1-1ubuntu1.10?arch=source&distro=bionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.5.1-1ubuntu1.10"}]}],"versions":["2.5.0~preview1-1ubuntu2","2.5.0-4ubuntu1","2.5.0-4ubuntu4","2.5.0-5ubuntu1","2.5.0-6ubuntu1","2.5.1-1ubuntu1","2.5.1-1ubuntu1.1","2.5.1-1ubuntu1.2","2.5.1-1ubuntu1.4","2.5.1-1ubuntu1.5","2.5.1-1ubuntu1.6","2.5.1-1ubuntu1.7","2.5.1-1ubuntu1.8","2.5.1-1ubuntu1.9"],"ecosystem_specific":{"availability":"No subscription required","binaries":[{"binary_name":"libruby2.5","binary_version":"2.5.1-1ubuntu1.10"},{"binary_name":"ruby2.5","binary_version":"2.5.1-1ubuntu1.10"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2021/UBUNTU-CVE-2021-32066.json"}},{"package":{"name":"ruby2.7","ecosystem":"Ubuntu:20.04:LTS","purl":"pkg:deb/ubuntu/ruby2.7@2.7.0-5ubuntu1.5?arch=source&distro=focal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.7.0-5ubuntu1.5"}]}],"versions":["2.7.0-1","2.7.0-2","2.7.0-3","2.7.0-4","2.7.0-4ubuntu1","2.7.0-5ubuntu1","2.7.0-5ubuntu1.1","2.7.0-5ubuntu1.2","2.7.0-5ubuntu1.3","2.7.0-5ubuntu1.4"],"ecosystem_specific":{"availability":"No subscription required","binaries":[{"binary_version":"2.7.0-5ubuntu1.5","binary_name":"libruby2.7"},{"binary_name":"ruby2.7","binary_version":"2.7.0-5ubuntu1.5"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2021/UBUNTU-CVE-2021-32066.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N"},{"type":"Ubuntu","score":"medium"}]}