{"id":"CVE-2023-21529","url":"https://www.cyber-defence.io/tools/cve/CVE-2023-21529","generatedAt":"2026-10-31T11:46:17.830Z","title":"Microsoft Exchange Server Deserialization of Untrusted Data Vulnerability","description":"Microsoft Exchange Server Remote Code Execution Vulnerability","published":"2023-02-14T20:15:12.000Z","lastModified":"2026-08-19T17:18:06.000Z","status":"Analyzed","sourceIdentifier":"secure@microsoft.com","cvss":{"version":"3.1","score":8.8,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"},"cwe":["CWE-502"],"affected":["microsoft/exchange server"],"epss":{"score":0.59294,"percentile":0.99117,"date":"2026-10-30","history":[{"date":"2026-09-24","score":0.59294,"percentile":0.99088}]},"kev":{"listed":true,"dateAdded":"2026-04-13","dueDate":"2026-04-27","knownRansomwareCampaignUse":"Known","notes":"Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.\nhttps://msrc.microsoft.com/update-guide/vulnerability/CVE-2023-21529 ; https://nvd.nist.gov/vuln/detail/CVE-2023-21529"},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"urgent","text":"Known to be exploited in the wild (CISA KEV, CISA remediation deadline 27 April 2026). Treat as an emergency change: patch or isolate now, then hunt for prior compromise."},"changes":[],"references":[{"url":"https://msrc.microsoft.com/update-guide/vulnerability/CVE-2023-21529","tags":["Patch","Vendor Advisory"],"source":"secure@microsoft.com"},{"url":"https://msrc.microsoft.com/update-guide/vulnerability/CVE-2023-21529","tags":["Patch","Vendor Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2023-21529","tags":["US Government Resource"],"source":"134c704f-9b21-4f2e-91b3-4a467353bcc0"},{"url":"https://www.microsoft.com/en-us/security/blog/2026/04/06/storm-1175-focuses-gaze-on-vulnerable-web-facing-assets-in-high-tempo-medusa-ransomware-operations/","tags":["Technical Description"],"source":"134c704f-9b21-4f2e-91b3-4a467353bcc0"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2023-21529","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}