{
  "document": {
    "category": "csaf_vex",
    "csaf_version": "2.0",
    "distribution": {
      "text": "Public",
      "tlp": {
        "label": "WHITE",
        "url": "https://www.first.org/tlp/"
      }
    },
    "lang": "en-US",
    "notes": [
      {
        "category": "general",
        "text": "To determine the support lifecycle for your software, see the Microsoft Support Lifecycle: https://support.microsoft.com/lifecycle",
        "title": "Additional Resources"
      },
      {
        "category": "legal_disclaimer",
        "text": "The information provided in the Microsoft Knowledge Base is provided \\\"as is\\\" without warranty of any kind. Microsoft disclaims all warranties, either express or implied, including the warranties of merchantability and fitness for a particular purpose. In no event shall Microsoft Corporation or its suppliers be liable for any damages whatsoever including direct, indirect, incidental, consequential, loss of business profits or special damages, even if Microsoft Corporation or its suppliers have been advised of the possibility of such damages. Some states do not allow the exclusion or limitation of liability for consequential or incidental damages so the foregoing limitation may not apply.",
        "title": "Disclaimer"
      }
    ],
    "publisher": {
      "category": "vendor",
      "contact_details": "secure@microsoft.com",
      "name": "Microsoft Security Response Center",
      "namespace": "https://msrc.microsoft.com"
    },
    "references": [
      {
        "category": "self",
        "summary": "CVE-2021-40528 The ElGamal implementation in Libgcrypt before 1.9.4 allows plaintext recovery because during interaction between two cryptographic libraries a certain dangerous combination of the prime defined by the receiver\u0027s public key the generator defined by the receiver\u0027s public key and the sender\u0027s ephemeral exponents can lead to a cross-configuration attack against OpenPGP. - VEX",
        "url": "https://msrc.microsoft.com/csaf/vex/2021/msrc_cve-2021-40528.json"
      },
      {
        "category": "external",
        "summary": "Microsoft Support Lifecycle",
        "url": "https://support.microsoft.com/lifecycle"
      },
      {
        "category": "external",
        "summary": "Common Vulnerability Scoring System",
        "url": "https://www.first.org/cvss"
      }
    ],
    "title": "The ElGamal implementation in Libgcrypt before 1.9.4 allows plaintext recovery because during interaction between two cryptographic libraries a certain dangerous combination of the prime defined by the receiver\u0027s public key the generator defined by the receiver\u0027s public key and the sender\u0027s ephemeral exponents can lead to a cross-configuration attack against OpenPGP.",
    "tracking": {
      "current_release_date": "2021-09-14T00:00:00.000Z",
      "generator": {
        "date": "2025-10-19T22:11:41.976Z",
        "engine": {
          "name": "MSRC Generator",
          "version": "1.0"
        }
      },
      "id": "msrc_CVE-2021-40528",
      "initial_release_date": "2021-09-02T00:00:00.000Z",
      "revision_history": [
        {
          "date": "2021-09-14T00:00:00.000Z",
          "legacy_version": "1",
          "number": "1",
          "summary": "Information published."
        }
      ],
      "status": "final",
      "version": "1"
    }
  },
  "product_tree": {
    "branches": [
      {
        "branches": [
          {
            "branches": [
              {
                "category": "product_version",
                "name": "1.0",
                "product": {
                  "name": "CBL Mariner 1.0",
                  "product_id": "16820"
                }
              }
            ],
            "category": "product_name",
            "name": "Azure Linux"
          },
          {
            "branches": [
              {
                "category": "product_version_range",
                "name": "\u003ccm1 libgcrypt 1.8.7-3",
                "product": {
                  "name": "\u003ccm1 libgcrypt 1.8.7-3",
                  "product_id": "1"
                }
              },
              {
                "category": "product_version",
                "name": "cm1 libgcrypt 1.8.7-3",
                "product": {
                  "name": "cm1 libgcrypt 1.8.7-3",
                  "product_id": "18997"
                }
              }
            ],
            "category": "product_name",
            "name": "libgcrypt"
          }
        ],
        "category": "vendor",
        "name": "Microsoft"
      }
    ],
    "relationships": [
      {
        "category": "default_component_of",
        "full_product_name": {
          "name": "\u003ccm1 libgcrypt 1.8.7-3 as a component of CBL Mariner 1.0",
          "product_id": "16820-1"
        },
        "product_reference": "1",
        "relates_to_product_reference": "16820"
      },
      {
        "category": "default_component_of",
        "full_product_name": {
          "name": "cm1 libgcrypt 1.8.7-3 as a component of CBL Mariner 1.0",
          "product_id": "18997-16820"
        },
        "product_reference": "18997",
        "relates_to_product_reference": "16820"
      }
    ]
  },
  "vulnerabilities": [
    {
      "cve": "CVE-2021-40528",
      "cwe": {
        "id": "CWE-327",
        "name": "Use of a Broken or Risky Cryptographic Algorithm"
      },
      "notes": [
        {
          "category": "general",
          "text": "mitre",
          "title": "Assigning CNA"
        }
      ],
      "product_status": {
        "fixed": [
          "18997-16820"
        ],
        "known_affected": [
          "16820-1"
        ]
      },
      "references": [
        {
          "category": "self",
          "summary": "CVE-2021-40528 The ElGamal implementation in Libgcrypt before 1.9.4 allows plaintext recovery because during interaction between two cryptographic libraries a certain dangerous combination of the prime defined by the receiver\u0027s public key the generator defined by the receiver\u0027s public key and the sender\u0027s ephemeral exponents can lead to a cross-configuration attack against OpenPGP. - VEX",
          "url": "https://msrc.microsoft.com/csaf/vex/2021/msrc_cve-2021-40528.json"
        }
      ],
      "remediations": [
        {
          "category": "vendor_fix",
          "date": "2021-09-14T00:00:00.000Z",
          "details": "1.8.7-3:Security Update:https://learn.microsoft.com/en-us/azure/azure-linux/tutorial-azure-linux-upgrade",
          "product_ids": [
            "16820-1"
          ],
          "url": "https://learn.microsoft.com/en-us/azure/azure-linux/tutorial-azure-linux-upgrade"
        }
      ],
      "scores": [
        {
          "cvss_v3": {
            "attackComplexity": "HIGH",
            "attackVector": "NETWORK",
            "availabilityImpact": "NONE",
            "baseScore": 5.9,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "HIGH",
            "environmentalsScore": 0.0,
            "integrityImpact": "NONE",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "temporalScore": 5.9,
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N",
            "version": "3.1"
          },
          "products": [
            "16820-1"
          ]
        }
      ],
      "title": "The ElGamal implementation in Libgcrypt before 1.9.4 allows plaintext recovery because during interaction between two cryptographic libraries a certain dangerous combination of the prime defined by the receiver\u0027s public key the generator defined by the receiver\u0027s public key and the sender\u0027s ephemeral exponents can lead to a cross-configuration attack against OpenPGP."
    }
  ]
}