{
  "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-2026-40356 In MIT Kerberos 5 (aka krb5) before 1.22.3, there is an integer underflow and resultant out-of-bounds read if an application calls gss_accept_sec_context() on a system with a NegoEx mechanism registered in /etc/gss/mech. An unauthenticated remote attacker can trigger this, possibly causing the process to terminate in parse_message. - VEX",
        "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-40356.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": "In MIT Kerberos 5 (aka krb5) before 1.22.3, there is an integer underflow and resultant out-of-bounds read if an application calls gss_accept_sec_context() on a system with a NegoEx mechanism registered in /etc/gss/mech. An unauthenticated remote attacker can trigger this, possibly causing the process to terminate in parse_message.",
    "tracking": {
      "current_release_date": "2026-06-03T01:43:26.000Z",
      "generator": {
        "date": "2026-06-03T07:57:49.872Z",
        "engine": {
          "name": "MSRC Generator",
          "version": "1.0"
        }
      },
      "id": "msrc_CVE-2026-40356",
      "initial_release_date": "2026-04-02T00:00:00.000Z",
      "revision_history": [
        {
          "date": "2026-05-01T01:03:54.000Z",
          "legacy_version": "1",
          "number": "1",
          "summary": "Information published."
        },
        {
          "date": "2026-05-11T14:42:40.000Z",
          "legacy_version": "2",
          "number": "2",
          "summary": "Information published."
        },
        {
          "date": "2026-06-03T01:43:26.000Z",
          "legacy_version": "3",
          "number": "3",
          "summary": "Information published."
        }
      ],
      "status": "final",
      "version": "3"
    }
  },
  "product_tree": {
    "branches": [
      {
        "branches": [
          {
            "branches": [
              {
                "category": "product_version",
                "name": "3.0",
                "product": {
                  "name": "Azure Linux 3.0",
                  "product_id": "17084"
                }
              },
              {
                "category": "product_version",
                "name": "2.0",
                "product": {
                  "name": "CBL Mariner 2.0",
                  "product_id": "17086"
                }
              }
            ],
            "category": "product_name",
            "name": "Azure Linux"
          },
          {
            "branches": [
              {
                "category": "product_version_range",
                "name": "\u003cazl3 krb5 0:1.21.3-3.azl3",
                "product": {
                  "name": "\u003cazl3 krb5 0:1.21.3-3.azl3",
                  "product_id": "3"
                }
              },
              {
                "category": "product_version",
                "name": "azl3 krb5 0:1.21.3-3.azl3",
                "product": {
                  "name": "azl3 krb5 0:1.21.3-3.azl3",
                  "product_id": "20902"
                }
              },
              {
                "category": "product_version_range",
                "name": "cbl2 krb5 0:1.19.4-5.cbl2",
                "product": {
                  "name": "cbl2 krb5 0:1.19.4-5.cbl2",
                  "product_id": "2"
                }
              },
              {
                "category": "product_version_range",
                "name": "\u003cazl3 krb5 0:1.21.3-4.azl3",
                "product": {
                  "name": "\u003cazl3 krb5 0:1.21.3-4.azl3",
                  "product_id": "1"
                }
              },
              {
                "category": "product_version",
                "name": "azl3 krb5 0:1.21.3-4.azl3",
                "product": {
                  "name": "azl3 krb5 0:1.21.3-4.azl3",
                  "product_id": "21405"
                }
              }
            ],
            "category": "product_name",
            "name": "krb5"
          }
        ],
        "category": "vendor",
        "name": "Microsoft"
      }
    ],
    "relationships": [
      {
        "category": "default_component_of",
        "full_product_name": {
          "name": "\u003cazl3 krb5 0:1.21.3-3.azl3 as a component of Azure Linux 3.0",
          "product_id": "17084-3"
        },
        "product_reference": "3",
        "relates_to_product_reference": "17084"
      },
      {
        "category": "default_component_of",
        "full_product_name": {
          "name": "azl3 krb5 0:1.21.3-3.azl3 as a component of Azure Linux 3.0",
          "product_id": "20902-17084"
        },
        "product_reference": "20902",
        "relates_to_product_reference": "17084"
      },
      {
        "category": "default_component_of",
        "full_product_name": {
          "name": "cbl2 krb5 0:1.19.4-5.cbl2 as a component of CBL Mariner 2.0",
          "product_id": "17086-2"
        },
        "product_reference": "2",
        "relates_to_product_reference": "17086"
      },
      {
        "category": "default_component_of",
        "full_product_name": {
          "name": "\u003cazl3 krb5 0:1.21.3-4.azl3 as a component of Azure Linux 3.0",
          "product_id": "17084-1"
        },
        "product_reference": "1",
        "relates_to_product_reference": "17084"
      },
      {
        "category": "default_component_of",
        "full_product_name": {
          "name": "azl3 krb5 0:1.21.3-4.azl3 as a component of Azure Linux 3.0",
          "product_id": "21405-17084"
        },
        "product_reference": "21405",
        "relates_to_product_reference": "17084"
      }
    ]
  },
  "vulnerabilities": [
    {
      "cve": "CVE-2026-40356",
      "cwe": {
        "id": "CWE-191",
        "name": "Integer Underflow (Wrap or Wraparound)"
      },
      "notes": [
        {
          "category": "general",
          "text": "mitre",
          "title": "Assigning CNA"
        }
      ],
      "product_status": {
        "fixed": [
          "20902-17084",
          "21405-17084"
        ],
        "known_affected": [
          "17084-3",
          "17086-2",
          "17084-1"
        ]
      },
      "references": [
        {
          "category": "self",
          "summary": "CVE-2026-40356 In MIT Kerberos 5 (aka krb5) before 1.22.3, there is an integer underflow and resultant out-of-bounds read if an application calls gss_accept_sec_context() on a system with a NegoEx mechanism registered in /etc/gss/mech. An unauthenticated remote attacker can trigger this, possibly causing the process to terminate in parse_message. - VEX",
          "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-40356.json"
        }
      ],
      "remediations": [
        {
          "category": "none_available",
          "date": "2026-05-01T01:03:54.000Z",
          "details": "There is no fix available for this vulnerability as of now",
          "product_ids": [
            "17086-2"
          ]
        },
        {
          "category": "vendor_fix",
          "date": "2026-05-01T01:03:54.000Z",
          "details": "0:1.21.3-4.azl3:Security Update:https://learn.microsoft.com/en-us/azure/azure-linux/tutorial-azure-linux-upgrade",
          "product_ids": [
            "17084-3",
            "17084-1"
          ],
          "url": "https://learn.microsoft.com/en-us/azure/azure-linux/tutorial-azure-linux-upgrade"
        }
      ],
      "scores": [
        {
          "cvss_v3": {
            "attackComplexity": "HIGH",
            "attackVector": "NETWORK",
            "availabilityImpact": "HIGH",
            "baseScore": 5.9,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "NONE",
            "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:N/I:N/A:H",
            "version": "3.1"
          },
          "products": [
            "17084-3",
            "17086-2",
            "17084-1"
          ]
        }
      ],
      "title": "In MIT Kerberos 5 (aka krb5) before 1.22.3, there is an integer underflow and resultant out-of-bounds read if an application calls gss_accept_sec_context() on a system with a NegoEx mechanism registered in /etc/gss/mech. An unauthenticated remote attacker can trigger this, possibly causing the process to terminate in parse_message."
    }
  ]
}