{
  "document": {
    "category": "csaf_security_advisory",
    "csaf_version": "2.0",
    "distribution": {
      "tlp": {
        "label": "WHITE"
      }
    },
    "lang": "nl",
    "notes": [
      {
        "category": "legal_disclaimer",
        "text": "The Netherlands Cyber Security Center (henceforth: NCSC-NL) maintains this page to enhance access to its information and security advisories. The use of this security advisory is subject to the following terms and conditions:\n\n    NCSC-NL makes every reasonable effort to ensure that the content of this page is kept up to date, and that it is accurate and complete. Nevertheless, NCSC-NL cannot entirely rule out the possibility of errors, and therefore cannot give any warranty in respect of its completeness, accuracy or continuous keeping up-to-date. The information contained in this security advisory is intended solely for the purpose of providing general information to professional users. No rights can be derived from the information provided therein.\n\n    NCSC-NL and the Kingdom of the Netherlands assume no legal liability or responsibility for any damage resulting from either the use or inability of use of this security advisory. This includes damage resulting from the inaccuracy of incompleteness of the information contained in the advisory.\n    This security advisory is subject to Dutch law. All disputes related to or arising from the use of this advisory will be submitted to the competent court in The Hague. This choice of means also applies to the court in summary proceedings."
      },
      {
        "category": "description",
        "text": "Microsoft heeft een kwetsbaarheid verholpen in Microsoft Exchange Server.",
        "title": "Feiten"
      },
      {
        "category": "description",
        "text": "De kwetsbaarheid betreft een cross-site scripting (XSS) probleem dat ontstaat door onjuiste neutralisatie van invoer tijdens het genereren van webpagina\u0027s. Een onbevoegde aanvaller kan hierdoor kwaadaardige scripts injecteren en spoofing-aanvallen uitvoeren over een netwerk. Dit komt doordat gebruikersinvoer onvoldoende wordt gesanitiseerd voordat deze in webpagina\u0027s wordt weergegeven. Misbruik van deze kwetsbaarheid kan leiden tot ongeautoriseerde acties binnen de context van de getroffen webapplicatie. De kwetsbaarheid treft specifiek Microsoft Exchange Server omgevingen waar de invoerafhandeling niet adequaat is beveiligd.",
        "title": "Interpretaties"
      },
      {
        "category": "description",
        "text": "Microsoft heeft, in afwachting van een definitieve oplossing, mitigerende maatregelen geimplementeerd in de Exchange Emergency Mitigation Service middels een out-of-band update. Deze service is standaard actief. Microsoft adviseert om voor de zekerheid te controleren of deze service daadwerkelijk actief is op de eigen Exchange Server. Zie bijgevoegde referenties voor meer informatie.",
        "title": "Oplossingen"
      },
      {
        "category": "general",
        "text": "medium",
        "title": "Kans"
      },
      {
        "category": "general",
        "text": "high",
        "title": "Schade"
      },
      {
        "category": "general",
        "text": "Improper Neutralization of Input During Web Page Generation (\u0027Cross-site Scripting\u0027)",
        "title": "CWE-79"
      }
    ],
    "publisher": {
      "category": "coordinator",
      "contact_details": "cert@ncsc.nl",
      "name": "Nationaal Cyber Security Centrum",
      "namespace": "https://www.ncsc.nl/"
    },
    "references": [
      {
        "category": "external",
        "summary": "Reference",
        "url": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-42897"
      }
    ],
    "title": "Kwetsbaarheid verholpen in Microsoft Exchange Server",
    "tracking": {
      "current_release_date": "2026-05-15T08:41:41.607495Z",
      "generator": {
        "date": "2025-08-04T16:30:00Z",
        "engine": {
          "name": "V.A.",
          "version": "1.3"
        }
      },
      "id": "NCSC-2026-0159",
      "initial_release_date": "2026-05-15T08:41:41.607495Z",
      "revision_history": [
        {
          "date": "2026-05-15T08:41:41.607495Z",
          "number": "1.0.0",
          "summary": "Initiele versie"
        }
      ],
      "status": "final",
      "version": "1.0.0"
    }
  },
  "product_tree": {
    "branches": [
      {
        "branches": [
          {
            "branches": [
              {
                "category": "product_version_range",
                "name": "vers:unknown/*",
                "product": {
                  "name": "vers:unknown/*",
                  "product_id": "CSAFPID-1"
                }
              }
            ],
            "category": "product_name",
            "name": "Microsoft Exchange Server 2016 Cumulative Update 23"
          },
          {
            "branches": [
              {
                "category": "product_version_range",
                "name": "vers:unknown/*",
                "product": {
                  "name": "vers:unknown/*",
                  "product_id": "CSAFPID-2"
                }
              }
            ],
            "category": "product_name",
            "name": "Microsoft Exchange Server 2019 Cumulative Update 14"
          },
          {
            "branches": [
              {
                "category": "product_version_range",
                "name": "vers:unknown/*",
                "product": {
                  "name": "vers:unknown/*",
                  "product_id": "CSAFPID-3"
                }
              }
            ],
            "category": "product_name",
            "name": "Microsoft Exchange Server 2019 Cumulative Update 15"
          },
          {
            "branches": [
              {
                "category": "product_version_range",
                "name": "vers:unknown/*",
                "product": {
                  "name": "vers:unknown/*",
                  "product_id": "CSAFPID-4"
                }
              }
            ],
            "category": "product_name",
            "name": "Microsoft Exchange Server Subscription Edition RTM"
          }
        ],
        "category": "vendor",
        "name": "Microsoft"
      }
    ]
  },
  "vulnerabilities": [
    {
      "cve": "CVE-2026-42897",
      "cwe": {
        "id": "CWE-79",
        "name": "Improper Neutralization of Input During Web Page Generation (\u0027Cross-site Scripting\u0027)"
      },
      "notes": [
        {
          "category": "other",
          "text": "Improper Neutralization of Input During Web Page Generation (\u0027Cross-site Scripting\u0027)",
          "title": "CWE-79"
        },
        {
          "category": "description",
          "text": "A cross-site scripting vulnerability in Microsoft Exchange Server allows unauthorized attackers to perform network-based spoofing by improperly neutralizing input during web page generation.",
          "title": "Summary"
        }
      ],
      "product_status": {
        "known_affected": [
          "CSAFPID-1",
          "CSAFPID-2",
          "CSAFPID-3",
          "CSAFPID-4"
        ]
      },
      "references": [
        {
          "category": "self",
          "summary": "CVE-2026-42897 | NCSC-NL Website",
          "url": "https://vulnerabilities.ncsc.nl/csaf/v2/2026/cve-2026-42897.json"
        }
      ],
      "scores": [
        {
          "cvss_v3": {
            "baseScore": 8.1,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N",
            "version": "3.1"
          },
          "products": [
            "CSAFPID-1",
            "CSAFPID-2",
            "CSAFPID-3",
            "CSAFPID-4"
          ]
        }
      ],
      "title": "CVE-2026-42897"
    }
  ]
}