{
  "document": {
    "acknowledgments": [
      {
        "names": [
          "Anonymous"
        ]
      },
      {
        "names": [
          "Vaibhavi Kalgutkar with Microsoft"
        ]
      }
    ],
    "aggregate_severity": {
      "namespace": "https://www.microsoft.com/en-us/msrc/security-update-severity-rating-system",
      "text": "Important"
    },
    "category": "csaf_security_advisory",
    "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"
      },
      {
        "category": "general",
        "text": "Required. The vulnerability documented by this CVE requires customer action to resolve.",
        "title": "Customer Action"
      }
    ],
    "publisher": {
      "category": "vendor",
      "contact_details": "secure@microsoft.com",
      "name": "Microsoft Security Response Center",
      "namespace": "https://msrc.microsoft.com"
    },
    "references": [
      {
        "category": "self",
        "summary": "CVE-2026-45503 Microsoft Exchange Server Information Disclosure Vulnerability - HTML",
        "url": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-45503"
      },
      {
        "category": "self",
        "summary": "CVE-2026-45503 Microsoft Exchange Server Information Disclosure Vulnerability - CSAF",
        "url": "https://msrc.microsoft.com/csaf/advisories/2026/msrc_cve-2026-45503.json"
      },
      {
        "category": "external",
        "summary": "Microsoft Exploitability Index",
        "url": "https://www.microsoft.com/en-us/msrc/exploitability-index?rtc=1"
      },
      {
        "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": "Microsoft Exchange Server Information Disclosure Vulnerability",
    "tracking": {
      "current_release_date": "2026-06-09T07:00:00.000Z",
      "generator": {
        "date": "2026-06-09T17:04:14.570Z",
        "engine": {
          "name": "MSRC Generator",
          "version": "1.0"
        }
      },
      "id": "msrc_CVE-2026-45503",
      "initial_release_date": "2026-06-09T07:00:00.000Z",
      "revision_history": [
        {
          "date": "2026-06-09T07:00:00.000Z",
          "legacy_version": "1",
          "number": "1",
          "summary": "Information published."
        }
      ],
      "status": "final",
      "version": "1"
    }
  },
  "product_tree": {
    "branches": [
      {
        "branches": [
          {
            "category": "product_version_range",
            "name": "\u003c15.01.2507.069",
            "product": {
              "name": "Microsoft Exchange Server 2016 Cumulative Update 23 \u003c15.01.2507.069",
              "product_id": "4"
            }
          },
          {
            "category": "product_version",
            "name": "15.01.2507.069",
            "product": {
              "name": "Microsoft Exchange Server 2016 Cumulative Update 23 15.01.2507.069",
              "product_id": "12039"
            }
          }
        ],
        "category": "product_name",
        "name": "Microsoft Exchange Server 2016 Cumulative Update 23"
      },
      {
        "branches": [
          {
            "category": "product_version_range",
            "name": "\u003c15.02.2562.043",
            "product": {
              "name": "Microsoft Exchange Server Subscription Edition RTM \u003c15.02.2562.043",
              "product_id": "1"
            }
          },
          {
            "category": "product_version",
            "name": "15.02.2562.043",
            "product": {
              "name": "Microsoft Exchange Server Subscription Edition RTM 15.02.2562.043",
              "product_id": "16792"
            }
          }
        ],
        "category": "product_name",
        "name": "Microsoft Exchange Server Subscription Edition RTM"
      },
      {
        "branches": [
          {
            "category": "product_version_range",
            "name": "\u003c15.02.1748.046",
            "product": {
              "name": "Microsoft Exchange Server 2019 Cumulative Update 15 \u003c15.02.1748.046",
              "product_id": "2"
            }
          },
          {
            "category": "product_version",
            "name": "15.02.1748.046",
            "product": {
              "name": "Microsoft Exchange Server 2019 Cumulative Update 15 15.02.1748.046",
              "product_id": "12502"
            }
          }
        ],
        "category": "product_name",
        "name": "Microsoft Exchange Server 2019 Cumulative Update 15"
      },
      {
        "branches": [
          {
            "category": "product_version_range",
            "name": "\u003c15.02.1544.041",
            "product": {
              "name": "Microsoft Exchange Server 2019 Cumulative Update 14 \u003c15.02.1544.041",
              "product_id": "3"
            }
          },
          {
            "category": "product_version",
            "name": "15.02.1544.041",
            "product": {
              "name": "Microsoft Exchange Server 2019 Cumulative Update 14 15.02.1544.041",
              "product_id": "12293"
            }
          }
        ],
        "category": "product_name",
        "name": "Microsoft Exchange Server 2019 Cumulative Update 14"
      }
    ]
  },
  "vulnerabilities": [
    {
      "cve": "CVE-2026-45503",
      "cwe": {
        "id": "CWE-285",
        "name": "Improper Authorization"
      },
      "notes": [
        {
          "category": "general",
          "text": "Microsoft",
          "title": "Assigning CNA"
        },
        {
          "category": "faq",
          "text": "An authenticated Outlook Web App user could exploit this issue by reusing a valid access token issued to their own mailbox to access attachments stored in another user\u2019s mailbox within the same Exchange organization, without authorization.",
          "title": "How could an attacker exploit this vulnerability?"
        },
        {
          "category": "faq",
          "text": "An attacker could gain unauthorized access to email attachments stored in other users\u2019 mailboxes within the same organization, which may include documents, images, or other files attached to emails.",
          "title": "What type of information could be disclosed by this vulnerability?"
        }
      ],
      "product_status": {
        "fixed": [
          "12039",
          "12293",
          "12502",
          "16792"
        ],
        "known_affected": [
          "1",
          "2",
          "3",
          "4"
        ]
      },
      "references": [
        {
          "category": "self",
          "summary": "CVE-2026-45503 Microsoft Exchange Server Information Disclosure Vulnerability - HTML",
          "url": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-45503"
        },
        {
          "category": "self",
          "summary": "CVE-2026-45503 Microsoft Exchange Server Information Disclosure Vulnerability - CSAF",
          "url": "https://msrc.microsoft.com/csaf/advisories/2026/msrc_cve-2026-45503.json"
        }
      ],
      "remediations": [
        {
          "category": "vendor_fix",
          "date": "2026-06-09T07:00:00.000Z",
          "details": "15.01.2507.069:Security Update:https://support.microsoft.com/help/5094144",
          "product_ids": [
            "4"
          ],
          "url": "https://support.microsoft.com/help/5094144"
        },
        {
          "category": "vendor_fix",
          "date": "2026-06-09T07:00:00.000Z",
          "details": "15.02.2562.043:Security Update:https://support.microsoft.com/help/5094139",
          "product_ids": [
            "1"
          ],
          "url": "https://support.microsoft.com/help/5094139"
        },
        {
          "category": "vendor_fix",
          "date": "2026-06-09T07:00:00.000Z",
          "details": "15.02.1748.046:Security Update:https://support.microsoft.com/help/5094140",
          "product_ids": [
            "2"
          ],
          "url": "https://support.microsoft.com/help/5094140"
        },
        {
          "category": "vendor_fix",
          "date": "2026-06-09T07:00:00.000Z",
          "details": "15.02.1544.041:Security Update:https://support.microsoft.com/help/5094142",
          "product_ids": [
            "3"
          ],
          "url": "https://support.microsoft.com/help/5094142"
        }
      ],
      "scores": [
        {
          "cvss_v3": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "NONE",
            "baseScore": 8.1,
            "baseSeverity": "HIGH",
            "confidentialityImpact": "HIGH",
            "environmentalsScore": 0.0,
            "exploitCodeMaturity": "UNPROVEN",
            "integrityImpact": "HIGH",
            "privilegesRequired": "LOW",
            "remediationLevel": "OFFICIAL_FIX",
            "reportConfidence": "CONFIRMED",
            "scope": "UNCHANGED",
            "temporalScore": 7.1,
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N/E:U/RL:O/RC:C",
            "version": "3.1"
          },
          "products": [
            "1",
            "2",
            "3",
            "4"
          ]
        }
      ],
      "threats": [
        {
          "category": "impact",
          "details": "Information Disclosure"
        },
        {
          "category": "exploit_status",
          "details": "Publicly Disclosed:No;Exploited:No;Latest Software Release:Exploitation Unlikely"
        }
      ],
      "title": "Microsoft Exchange Server Information Disclosure Vulnerability"
    }
  ]
}