{"id":"UBUNTU-CVE-2021-36647","details":"Use of a Broken or Risky Cryptographic Algorithm in the function mbedtls_mpi_exp_mod() in lignum.c in Mbed TLS Mbed TLS all versions before 3.0.0, 2.27.0 or 2.16.11 allows attackers with access to precise enough timing and memory access information (typically an untrusted operating system attacking a secure enclave such as SGX or the TrustZone secure world) to recover the private keys used in RSA.","modified":"2026-04-22T12:57:13.166506Z","published":"2023-01-17T21:15:00Z","upstream":["CVE-2021-36647"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2021-36647"},{"type":"REPORT","url":"https://kouzili.com/Load-Step.pdf"},{"type":"REPORT","url":"https://tls.mbed.org/tech-updates/security-advisories/mbedtls-security-advisory-2021-07-1"},{"type":"REPORT","url":"https://github.com/ARMmbed/mbedtls/releases/"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2021-36647"}],"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/2021/UBUNTU-CVE-2021-36647.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/2021/UBUNTU-CVE-2021-36647.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_version":"2.16.4-1ubuntu2+esm1","binary_name":"libmbedcrypto3"},{"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/2021/UBUNTU-CVE-2021-36647.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N"},{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N"},{"type":"Ubuntu","score":"medium"}]}