{ "schemaVersion": 1, "attribution": [ { "source": "CISA Known Exploited Vulnerabilities", "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog", "licence": "US government work" }, { "source": "GitHub Advisory Database", "url": "https://github.com/advisories", "licence": "CC BY 4.0" }, { "source": "Have I Been Pwned", "url": "https://haveibeenpwned.com/", "licence": "CC BY 4.0" }, { "source": "CVE Program (CVE records)", "url": "https://www.cve.org/Legal/TermsOfUse", "licence": "CVE Terms of Use", "notice": "Copyright © 1999-2026, The MITRE Corporation. CVE is a trademark and the CVE logo is a registered trademark of The MITRE Corporation.", "terms": "CVE Usage: MITRE hereby grants you a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable copyright license to reproduce, prepare derivative works of, publicly display, publicly perform, sublicense, and distribute Common Vulnerabilities and Exposures (CVE™). Any copy you make for such purposes is authorized provided that you reproduce MITRE's copyright designation and this license in any such copy." }, { "source": "FIRST EPSS", "url": "https://www.first.org/epss/", "licence": "free to use; FIRST requests attribution" } ], "record": { "id": "CVE-2021-26855", "sourceURL": "https://www.cve.org/CVERecord?id=CVE-2021-26855", "idYear": 2021, "status": "PUBLISHED", "publishedAt": "2021-03-02T23:55:26.000Z", "updatedAt": "2026-08-19T16:30:15.282Z", "importedAt": "2026-10-24T01:56:26.894Z", "snapshot": { "id": "cve_2026-10-24_midnight_baseline", "at": "2026-10-24T00:00:00.000Z", "source": "https://github.com/CVEProject/cvelistV5/releases/tag/cve_2026-10-24_0100Z" }, "facts": { "title": "Microsoft Exchange Server Remote Code Execution Vulnerability", "summary": "Microsoft Exchange Server Remote Code Execution Vulnerability", "affected": [ { "vendor": "Microsoft", "product": "Microsoft Exchange Server 2013 Cumulative Update 21", "platforms": [ "x64-based Systems" ], "versions": [ { "version": "15.00.0", "status": "affected", "versionType": "custom", "lessThan": "15.00.1395.012" } ] }, { "vendor": "Microsoft", "product": "Microsoft Exchange Server 2013 Cumulative Update 22", "platforms": [ "x64-based Systems" ], "versions": [ { "version": "15.00.0", "status": "affected", "versionType": "custom", "lessThan": "15.00.1473.006" } ] }, { "vendor": "Microsoft", "product": "Microsoft Exchange Server 2013 Cumulative Update 23", "platforms": [ "x64-based Systems" ], "versions": [ { "version": "15.00.0", "status": "affected", "versionType": "custom", "lessThan": "15.00.1497.012" } ] }, { "vendor": "Microsoft", "product": "Microsoft Exchange Server 2016 Cumulative Update 10", "platforms": [ "x64-based Systems" ], "versions": [ { "version": "15.01.0", "status": "affected", "versionType": "custom", "lessThan": "15.01.1531.012" } ] }, { "vendor": "Microsoft", "product": "Microsoft Exchange Server 2016 Cumulative Update 11", "platforms": [ "x64-based Systems" ], "versions": [ { "version": "15.01.0", "status": "affected", "versionType": "custom", "lessThan": "15.01.1591.018" } ] }, { "vendor": "Microsoft", "product": "Microsoft Exchange Server 2016 Cumulative Update 12", "platforms": [ "x64-based Systems" ], "versions": [ { "version": "15.01.0", "status": "affected", "versionType": "custom", "lessThan": "15.01.1713.010" } ] }, { "vendor": "Microsoft", "product": "Microsoft Exchange Server 2016 Cumulative Update 13", "platforms": [ "x64-based Systems" ], "versions": [ { "version": "15.01.0", "status": "affected", "versionType": "custom", "lessThan": "15.01.1779.008" } ] }, { "vendor": "Microsoft", "product": "Microsoft Exchange Server 2016 Cumulative Update 14", "platforms": [ "x64-based Systems" ], "versions": [ { "version": "15.01.0", "status": "affected", "versionType": "custom", "lessThan": "15.01.1847.012" } ] }, { "vendor": "Microsoft", "product": "Microsoft Exchange Server 2016 Cumulative Update 15", "platforms": [ "x64-based Systems" ], "versions": [ { "version": "15.01.0", "status": "affected", "versionType": "custom", "lessThan": "15.01.1913.012" } ] }, { "vendor": "Microsoft", "product": "Microsoft Exchange Server 2016 Cumulative Update 16", "platforms": [ "x64-based Systems" ], "versions": [ { "version": "15.01.0", "status": "affected", "versionType": "custom", "lessThan": "15.01.1979.008" } ] }, { "vendor": "Microsoft", "product": "Microsoft Exchange Server 2016 Cumulative Update 17", "platforms": [ "x64-based Systems" ], "versions": [ { "version": "15.01.0", "status": "affected", "versionType": "custom", "lessThan": "15.01.2044.013" } ] }, { "vendor": "Microsoft", "product": "Microsoft Exchange Server 2016 Cumulative Update 18", "platforms": [ "x64-based Systems" ], "versions": [ { "version": "15.01.0", "status": "affected", "versionType": "custom", "lessThan": "15.01.2106.013" } ] }, { "vendor": "Microsoft", "product": "Microsoft Exchange Server 2016 Cumulative Update 19", "platforms": [ "x64-based Systems" ], "versions": [ { "version": "15.01.0", "status": "affected", "versionType": "custom", "lessThan": "15.01.2176.009" } ] }, { "vendor": "Microsoft", "product": "Microsoft Exchange Server 2016 Cumulative Update 8", "platforms": [ "x64-based Systems" ], "versions": [ { "version": "15.01.0", "status": "affected", "versionType": "custom", "lessThan": "15.01.1415.010" } ] }, { "vendor": "Microsoft", "product": "Microsoft Exchange Server 2016 Cumulative Update 9", "platforms": [ "x64-based Systems" ], "versions": [ { "version": "15.01.0", "status": "affected", "versionType": "custom", "lessThan": "15.01.1466.016" } ] }, { "vendor": "Microsoft", "product": "Microsoft Exchange Server 2019", "platforms": [ "x64-based Systems" ], "versions": [ { "version": "15.02.0", "status": "affected", "versionType": "custom", "lessThan": "15.02.0221.018" } ] }, { "vendor": "Microsoft", "product": "Microsoft Exchange Server 2019 Cumulative Update 1", "platforms": [ "x64-based Systems" ], "versions": [ { "version": "15.02.0", "status": "affected", "versionType": "custom", "lessThan": "15.01.1979.006" } ] }, { "vendor": "Microsoft", "product": "Microsoft Exchange Server 2019 Cumulative Update 2", "platforms": [ "x64-based Systems" ], "versions": [ { "version": "15.02.0", "status": "affected", "versionType": "custom", "lessThan": "15.02.0397.011" } ] }, { "vendor": "Microsoft", "product": "Microsoft Exchange Server 2019 Cumulative Update 3", "platforms": [ "x64-based Systems" ], "versions": [ { "version": "15.02.0", "status": "affected", "versionType": "custom", "lessThan": "15.02.0464.015" } ] }, { "vendor": "Microsoft", "product": "Microsoft Exchange Server 2019 Cumulative Update 4", "platforms": [ "x64-based Systems" ], "versions": [ { "version": "15.02.0", "status": "affected", "versionType": "custom", "lessThan": "15.02.0659.012" } ] }, { "vendor": "Microsoft", "product": "Microsoft Exchange Server 2019 Cumulative Update 5", "platforms": [ "x64-based Systems" ], "versions": [ { "version": "15.02.0", "status": "affected", "versionType": "custom", "lessThan": "15.02.0595.008" } ] }, { "vendor": "Microsoft", "product": "Microsoft Exchange Server 2019 Cumulative Update 6", "platforms": [ "x64-based Systems" ], "versions": [ { "version": "15.02.0", "status": "affected", "versionType": "custom", "lessThan": "15.02.0529.013" } ] }, { "vendor": "Microsoft", "product": "Microsoft Exchange Server 2019 Cumulative Update 7", "platforms": [ "x64-based Systems" ], "versions": [ { "version": "15.02.0", "status": "affected", "versionType": "custom", "lessThan": "15.02.0721.013" } ] }, { "vendor": "Microsoft", "product": "Microsoft Exchange Server 2019 Cumulative Update 8", "platforms": [ "x64-based Systems" ], "versions": [ { "version": "15.02.0", "status": "affected", "versionType": "custom", "lessThan": "15.02.0792.010" } ] } ] } } }