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{"cisaActionDue": "2021-04-16", "cisaExploitAdd": "2021-11-03", "cisaRequiredAction": "Apply updates per vendor instructions.", "cisaVulnerabilityName": "Microsoft Exchange Server Remote Code Execution Vulnerability", "configurations": [{"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:a:microsoft:exchange_server:2013:cumulative_update_21:*:*:*:*:*:*", "matchCriteriaId": "B560F8FD-068E-4A16-A37F-A62DCE88FCF2", "vulnerable": true}, {"criteria": "cpe:2.3:a:microsoft:exchange_server:2013:cumulative_update_22:*:*:*:*:*:*", "matchCriteriaId": "751FD35F-2ECD-4B75-9589-988CC6AD3058", "vulnerable": true}, {"criteria": "cpe:2.3:a:microsoft:exchange_server:2013:cumulative_update_23:*:*:*:*:*:*", "matchCriteriaId": "DA166F2A-D83B-4D50-AD0B-668D813E0585", "vulnerable": true}, {"criteria": "cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_10:*:*:*:*:*:*", "matchCriteriaId": "63E362CB-CF75-4B7E-A4B1-D6D84AFCBB68", "vulnerable": true}, {"criteria": "cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_11:*:*:*:*:*:*", "matchCriteriaId": "9BE04790-85A2-4078-88CE-1787BC5172E7", "vulnerable": true}, {"criteria": "cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_12:*:*:*:*:*:*", "matchCriteriaId": "CCF101BE-27FD-4E2D-A694-C606BD3D1ED7", "vulnerable": true}, {"criteria": "cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_13:*:*:*:*:*:*", "matchCriteriaId": "4DF5BDB5-205D-4B64-A49A-0152AFCF4A13", "vulnerable": true}, {"criteria": "cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_14:*:*:*:*:*:*", "matchCriteriaId": "55284CF7-0D04-4216-83FE-4B1F9CA94207", "vulnerable": true}, {"criteria": "cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_15:*:*:*:*:*:*", "matchCriteriaId": "CA2CE223-AA49-49E6-AC32-59270EFF55AD", "vulnerable": true}, {"criteria": "cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_16:*:*:*:*:*:*", "matchCriteriaId": "4830D6A9-AF74-480C-8F69-8648CD619980", "vulnerable": true}, {"criteria": "cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_17:*:*:*:*:*:*", "matchCriteriaId": "079E1E3F-FF25-4B0D-AC98-191D6455A014", "vulnerable": true}, {"criteria": "cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_18:*:*:*:*:*:*", "matchCriteriaId": "29805EC7-6403-44B9-91EC-109C087E98EB", "vulnerable": true}, {"criteria": "cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_19:*:*:*:*:*:*", "matchCriteriaId": "28FCA0E8-7D27-4746-9731-91B834CA3E64", "vulnerable": true}, {"criteria": "cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_8:*:*:*:*:*:*", "matchCriteriaId": "075E907F-AF2F-4C31-86C7-51972BE412A1", "vulnerable": true}, {"criteria": "cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_9:*:*:*:*:*:*", "matchCriteriaId": "69AF19DC-3D65-49A8-A85F-511085CDF27B", "vulnerable": true}, {"criteria": "cpe:2.3:a:microsoft:exchange_server:2019:-:*:*:*:*:*:*", "matchCriteriaId": "40D8A6DB-9225-4A3F-AD76-192F6CCCF002", "vulnerable": true}, {"criteria": "cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_1:*:*:*:*:*:*", "matchCriteriaId": "051DE6C4-7456-4C42-BC51-253208AADB4E", "vulnerable": true}, {"criteria": "cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_2:*:*:*:*:*:*", "matchCriteriaId": "EE320413-D2C9-4B28-89BF-361B44A3F0FF", "vulnerable": true}, {"criteria": "cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_3:*:*:*:*:*:*", "matchCriteriaId": "104F96DC-E280-4E0A-8586-B043B55888C2", "vulnerable": true}, {"criteria": "cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_4:*:*:*:*:*:*", "matchCriteriaId": "73B3B3FE-7E85-4B86-A983-2C410FFEF4B8", "vulnerable": true}, {"criteria": "cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_5:*:*:*:*:*:*", "matchCriteriaId": "8A9FB275-7F17-48B2-B528-BE89309D2AF5", "vulnerable": true}, {"criteria": "cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_6:*:*:*:*:*:*", "matchCriteriaId": "D4AB3C25-CEA8-4D66-AEE4-953C8B17911A", "vulnerable": true}, {"criteria": "cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_7:*:*:*:*:*:*", "matchCriteriaId": "36CE5C6D-9A04-41F5-AE7C-265779833649", "vulnerable": true}, {"criteria": "cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_8:*:*:*:*:*:*", "matchCriteriaId": "44ECF39A-1DE1-4870-A494-06A53494338D", "vulnerable": true}], "negate": false, "operator": "OR"}]}], "cveTags": [], "descriptions": [{"lang": "en", "value": "Microsoft Exchange Server Remote Code Execution Vulnerability"}, {"lang": "es", "value": "Una Vulnerabilidad de Ejecuci\u00f3n de c\u00f3digo remota de Microsoft Exchange Server. Este ID de CVE es diferente de CVE-2021-26412, CVE-2021-26854, CVE-2021-26857, CVE-2021-26858, CVE-2021-27065, CVE-2021-27078"}], "id": "CVE-2021-26855", "lastModified": "2025-10-30T19:55:58.670", "metrics": {"cvssMetricV2": [{"acInsufInfo": false, "baseSeverity": "HIGH", "cvssData": {"accessComplexity": "LOW", "accessVector": "NETWORK", "authentication": "NONE", "availabilityImpact": "PARTIAL", "baseScore": 7.5, "confidentialityImpact": "PARTIAL", "integrityImpact": "PARTIAL", "vectorString": "AV:N/AC:L/Au:N/C:P/I:P/A:P", "version": "2.0"}, "exploitabilityScore": 10.0, "impactScore": 6.4, "obtainAllPrivilege": false, "obtainOtherPrivilege": false, "obtainUserPrivilege": false, "source": "nvd@nist.gov", "type": "Primary", "userInteractionRequired": false}], "cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 9.1, "baseSeverity": "CRITICAL", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N", "version": "3.1"}, "exploitabilityScore": 3.9, "impactScore": 5.2, "source": "secure@microsoft.com", "type": "Secondary"}, {"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 9.8, "baseSeverity": "CRITICAL", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "version": "3.1"}, "exploitabilityScore": 3.9, "impactScore": 5.9, "source": "nvd@nist.gov", "type": "Secondary"}]}, "published": "2021-03-03T00:15:12.103", "references": [{"source": "secure@microsoft.com", "tags": ["Exploit", "Third Party Advisory", "VDB Entry"], "url": "http://packetstormsecurity.com/files/161846/Microsoft-Exchange-2019-SSRF-Arbitrary-File-Write.html"}, {"source": "secure@microsoft.com", "tags": ["Exploit", "Third Party Advisory", "VDB Entry"], "url": "http://packetstormsecurity.com/files/161938/Microsoft-Exchange-ProxyLogon-Remote-Code-Execution.html"}, {"source": "secure@microsoft.com", "tags": ["Exploit", "Third Party Advisory", "VDB Entry"], "url": "http://packetstormsecurity.com/files/162610/Microsoft-Exchange-2019-Unauthenticated-Email-Download.html"}, {"source": "secure@microsoft.com", "tags": ["Exploit", "Third Party Advisory", "VDB Entry"], "url": "http://packetstormsecurity.com/files/162736/Microsoft-Exchange-ProxyLogon-Collector.html"}, {"source": "secure@microsoft.com", "tags": ["Patch", "Vendor Advisory"], "url": "https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-26855"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Exploit", "Third Party Advisory", "VDB Entry"], "url": "http://packetstormsecurity.com/files/161846/Microsoft-Exchange-2019-SSRF-Arbitrary-File-Write.html"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Exploit", "Third Party Advisory", "VDB Entry"], "url": "http://packetstormsecurity.com/files/161938/Microsoft-Exchange-ProxyLogon-Remote-Code-Execution.html"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Exploit", "Third Party Advisory", "VDB Entry"], "url": "http://packetstormsecurity.com/files/162610/Microsoft-Exchange-2019-Unauthenticated-Email-Download.html"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Exploit", "Third Party Advisory", "VDB Entry"], "url": "http://packetstormsecurity.com/files/162736/Microsoft-Exchange-ProxyLogon-Collector.html"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Patch", "Vendor Advisory"], "url": "https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-26855"}, {"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "tags": ["US Government Resource"], "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-26855"}], "sourceIdentifier": "secure@microsoft.com", "vulnStatus": "Analyzed", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-918"}], "source": "nvd@nist.gov", "type": "Primary"}, {"description": [{"lang": "en", "value": "CWE-918"}], "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary"}]}

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