{"schema_version":"1","data":[{"id":3655,"advisory_id":"d72d25e6-82b3-4acc-8bc2-16ad62549435","revision":1,"source_id":"core-kev","source_url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2021-26858","source_published_at":"2021-11-03T00:00:00+00:00","published_at":"2026-10-24T21:38:32.669635+00:00","extraction_method":"structured","technologies":["core-kev","exchange-server"],"cve_ids":["CVE-2021-26858"],"event_types":["advisory"],"payload":{"kind":"advisory","title":"Microsoft Exchange Server Remote Code Execution Vulnerability","summary":"Microsoft Exchange Server contains an unspecified vulnerability that allows for remote code execution. This vulnerability is part of the ProxyLogon exploit chain. CISA required action: Apply updates per vendor instructions.","evidence":"kev:CVE-2021-26858","products":[{"name":{"value":"Exchange Server","evidence":"/product"},"prerequisites":[],"fixed_versions":[],"affected_versions":[]}],"severity":"unknown","structured":{"id":"CVE-2021-26858","aliases":["CVE-2021-26858"],"affected":[],"modified":"2021-11-03T00:00:00.000Z","provider":"kev","references":["https://www.cisa.gov/known-exploited-vulnerabilities-catalog"],"exploitation":{"cwes":[],"cveID":"CVE-2021-26858","notes":"Reference CISA's ED 21-02 (https://www.cisa.gov/news-events/directives/ed-21-02-mitigate-microsoft-exchange-premises-product-vulnerabilities) for further guidance and requirements. Note: The due date for addressing this vulnerability aligns with the requirements outlined in ED 21-02. https://nvd.nist.gov/vuln/detail/CVE-2021-26858","dueDate":"2022-05-03","product":"Exchange Server","dateAdded":"2021-11-03","vendorProject":"Microsoft","requiredAction":"Apply updates per vendor instructions.","known_exploited":true,"shortDescription":"Microsoft Exchange Server contains an unspecified vulnerability that allows for remote code execution. This vulnerability is part of the ProxyLogon exploit chain.","vulnerabilityName":"Microsoft Exchange Server Remote Code Execution Vulnerability","knownRansomwareCampaignUse":"Known"}},"related_cves":[{"value":"CVE-2021-26858","evidence":"/cveID"}],"security_relevant":true,"severity_evidence":null}}],"next_after":3655,"next_before":3655}