{"id":"CVE-2021-26858","title":"Microsoft Exchange Server Remote Code Execution Vulnerability","summary":"Microsoft Exchange Server Remote Code Execution Vulnerability","severity":"high","cvss":7.8,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H","vendor":"microsoft","product":"exchange_server","affected":["exchange_server = 2013","exchange_server = 2016","exchange_server = 2019"],"published":"2021-03-03","updated":"2026-10-01","sourceUpdated":"2026-10-01T21:17:16.777","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2021-26858","references":[{"url":"https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-26858","label":"secure@microsoft.com"},{"url":"https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-26858","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-26858","label":"134c704f-9b21-4f2e-91b3-4a467353bcc0"}],"tags":["nvd","kev","in-the-wild","cve.org","exploit-available"],"epss":0.93651,"epssPercentile":0.99842,"kev":true,"kevDateAdded":"2021-11-03","kevDueDate":"2022-05-03","kevRansomware":true,"exploited":true,"exploitAvailable":true,"ssvc":{"exploitation":"active","automatable":"yes","technicalImpact":"total","timestamp":"2026-08-12T03:55:36.937537Z"},"ingestedAt":"2026-08-12T19:54:25.711Z","slug":"CVE-2021-26858","body":"## Overview\n\nMicrosoft Exchange Server Remote Code Execution Vulnerability\n\n## Affected\n\n- `exchange_server = 2013`\n- `exchange_server = 2016`\n- `exchange_server = 2019`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"abyssal","depthScore":92,"depthScoreParts":{"impact":42.9,"likelihood":18.7,"exploitation":25,"ransomware":5},"changes":[{"seq":214721,"id":"CVE-2021-26858","ts":1790895848022,"field":"zero_day","old":"true","new":"false"},{"seq":214707,"id":"CVE-2021-26858","ts":1790888514396,"field":"exploit_available","old":"false","new":"true"}]}