ubuntu-cve-2021-36647
Vulnerability from osv_ubuntu
Published
2023-01-17 21:15
Modified
2026-04-22 07:40
Summary
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.

Severity
4.7 (Medium)
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N
4.7 (Medium)
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N
N/A (UNKNOWN)
medium
References
To clipboard 

{
  "affected": [
    {
      "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"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:16.04:LTS",
        "name": "mbedtls",
        "purl": "pkg:deb/ubuntu/mbedtls@2.2.1-2ubuntu0.3?arch=source\u0026distro=xenial"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "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": "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"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:18.04:LTS",
        "name": "mbedtls",
        "purl": "pkg:deb/ubuntu/mbedtls@2.8.0-1ubuntu0.1~esm1?arch=source\u0026distro=esm-apps/bionic"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "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": "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"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:20.04:LTS",
        "name": "mbedtls",
        "purl": "pkg:deb/ubuntu/mbedtls@2.16.4-1ubuntu2+esm1?arch=source\u0026distro=esm-apps/focal"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2.16.2-1",
        "2.16.3-1",
        "2.16.4-1ubuntu2",
        "2.16.4-1ubuntu2+esm1"
      ]
    }
  ],
  "aliases": [],
  "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.",
  "id": "UBUNTU-CVE-2021-36647",
  "modified": "2026-04-22T07:40:06Z",
  "published": "2023-01-17T21:15:00Z",
  "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"
    }
  ],
  "related": [],
  "schema_version": "1.7.0",
  "severity": [
    {
      "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": "CVSS_V3"
    },
    {
      "score": "medium",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2021-36647"
  ]
}



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