{"id":"UBUNTU-CVE-2020-36477","details":"An issue was discovered in Mbed TLS before 2.24.0. The verification of X.509 certificates when matching the expected common name (the cn argument of mbedtls_x509_crt_verify) with the actual certificate name is mishandled: when the subjecAltName extension is present, the expected name is compared to any name in that extension regardless of its type. This means that an attacker could impersonate a 4-byte or 16-byte domain by getting a certificate for the corresponding IPv4 or IPv6 address (this would require the attacker to control that IP address, though).","modified":"2026-04-22T12:41:55.698464Z","published":"2021-08-23T02:15:00Z","upstream":["CVE-2020-36477"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2020-36477"},{"type":"REPORT","url":"https://github.com/ARMmbed/mbedtls/issues/3498"},{"type":"REPORT","url":"https://github.com/ARMmbed/mbedtls/releases/tag/v2.24.0"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2020-36477"}],"affected":[{"package":{"name":"mbedtls","ecosystem":"Ubuntu:16.04:LTS","purl":"pkg:deb/ubuntu/mbedtls@2.2.1-2ubuntu0.3?arch=source&distro=xenial"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.1.2-1","2.2.0-1","2.2.1-1","2.2.1-2","2.2.1-2ubuntu0.1","2.2.1-2ubuntu0.2","2.2.1-2ubuntu0.3"],"ecosystem_specific":{"binaries":[{"binary_name":"libmbedcrypto0","binary_version":"2.2.1-2ubuntu0.3"},{"binary_name":"libmbedtls10","binary_version":"2.2.1-2ubuntu0.3"},{"binary_name":"libmbedx509-0","binary_version":"2.2.1-2ubuntu0.3"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2020/UBUNTU-CVE-2020-36477.json"}},{"package":{"name":"mbedtls","ecosystem":"Ubuntu:Pro:18.04:LTS","purl":"pkg:deb/ubuntu/mbedtls@2.8.0-1ubuntu0.1~esm1?arch=source&distro=esm-apps/bionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.5.1-1ubuntu1","2.6.0-1","2.7.0-2","2.8.0-1","2.8.0-1ubuntu0.1~esm1"],"ecosystem_specific":{"binaries":[{"binary_name":"libmbedcrypto1","binary_version":"2.8.0-1ubuntu0.1~esm1"},{"binary_name":"libmbedtls10","binary_version":"2.8.0-1ubuntu0.1~esm1"},{"binary_name":"libmbedx509-0","binary_version":"2.8.0-1ubuntu0.1~esm1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2020/UBUNTU-CVE-2020-36477.json"}},{"package":{"name":"mbedtls","ecosystem":"Ubuntu:Pro:20.04:LTS","purl":"pkg:deb/ubuntu/mbedtls@2.16.4-1ubuntu2+esm1?arch=source&distro=esm-apps/focal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.16.2-1","2.16.3-1","2.16.4-1ubuntu2","2.16.4-1ubuntu2+esm1"],"ecosystem_specific":{"binaries":[{"binary_name":"libmbedcrypto3","binary_version":"2.16.4-1ubuntu2+esm1"},{"binary_name":"libmbedtls12","binary_version":"2.16.4-1ubuntu2+esm1"},{"binary_name":"libmbedx509-0","binary_version":"2.16.4-1ubuntu2+esm1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2020/UBUNTU-CVE-2020-36477.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:N/I:H/A:N"},{"type":"Ubuntu","score":"medium"}]}