{"id":"CVE-2026-55009","published":"2026-07-14T17:05:02Z","modified":"2026-10-28T20:01:39Z","title":"Microsoft Exchange Server Elevation of Privilege Vulnerability","vendor":"Microsoft","product":"Microsoft Exchange Server 2016 Cumulative Update 23","tier":"tail","description":{"text":"Deserialization of untrusted data in Microsoft Exchange Server allows an authorized attacker to elevate privileges locally.","provenance":"source","from":"CVE.org"},"cvss":{"score":7.8,"severity":"HIGH","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C","provenance":"source","from":"CVE.org CNA"},"epss":{"score":0.02513,"percentile":0.84733,"provenance":"source"},"cwes":[{"id":"CWE-502","name":"Deserialization of Untrusted Data"}],"references":[{"url":"https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-55009","tags":["vendor-advisory","patch"]}],"priority":{"score":22.4,"factors":[{"name":"EPSS percentile","points":16.95},{"name":"CVSS severity","points":5.46}]},"vendorSlug":"microsoft","affectedVersions":[{"vendor":"Microsoft","product":"Microsoft Exchange Server 2016 Cumulative Update 23","versions":[">= 15.01.0.0, < 15.01.2507.071"]},{"vendor":"Microsoft","product":"Microsoft Exchange Server 2019 Cumulative Update 14","versions":[">= 15.02.0.0, < 15.02.1544.043"]},{"vendor":"Microsoft","product":"Microsoft Exchange Server 2019 Cumulative Update 15","versions":[">= 15.02.0.0, < 15.02.1748.048"]},{"vendor":"Microsoft","product":"Microsoft Exchange Server Subscription Edition RTM","versions":[">= 15.02.0.0, < 15.02.2562.045"]}],"euvd":{"id":"EUVD-2026-44027","exploited":false,"provenance":"source"},"lineage":{"familyId":"fam-class-microsoft-exchange-server-cwe-502"}}