{"id":"CVE-2026-56191","url":"https://www.cyber-defence.io/tools/cve/CVE-2026-56191","generatedAt":"2026-10-28T02:18:21.808Z","title":"Improper authentication in Microsoft Exchange Online allows an unauthorized attacker to perform tampering over a network.","description":"Improper authentication in Microsoft Exchange Online allows an unauthorized attacker to perform tampering over a network.","published":"2026-07-24T01:17:36.000Z","lastModified":"2026-10-24T13:10:00.000Z","status":"Analyzed","sourceIdentifier":"secure@microsoft.com","cvss":{"version":"3.1","score":10,"severity":"CRITICAL","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H"},"cwe":["CWE-287"],"affected":["microsoft/exchange online"],"epss":{"score":0.00901,"percentile":0.59441,"date":"2026-10-26","history":[]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"high","text":"High impact if exploited, but EPSS currently rates exploitation as unlikely (0.90%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit."},"changes":[],"references":[{"url":"https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-56191","tags":["Vendor Advisory"],"source":"secure@microsoft.com"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-56191","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."}