{"id":"CVE-2026-66307","aliases":[],"cve":{"records":[{"id":"CVE-2026-66307","source":"microsoft","state":"PUBLISHED","reasons":[],"replacements":[],"disputed":false,"unsupportedWhenAssigned":false,"reserved":"2026-07-24T18:06:51.294Z","published":"2026-09-08T18:39:44.434Z","modified":"2026-10-30T21:57:48.039Z"}],"publishers":[{"name":"microsoft","role":"CNA","organizationId":"f38d906d-7342-40ea-92c1-6c4a2c6478c8","modified":"2026-10-30T21:57:48.039Z"},{"name":"CISA-ADP","role":"ADP","organizationId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","modified":"2026-09-08T19:17:17.096Z"}],"references":[{"url":"https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-66307","tags":["vendor-advisory","patch"],"source":"microsoft"}],"weaknesses":[{"id":"CWE-191","description":"CWE-191: Integer Underflow (Wrap or Wraparound)","source":"microsoft"}],"applicability":[{"source":"microsoft","statements":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:a:microsoft:skype_for_business_server_2015:*:cu13:*:*:*:*:*:*","versionStartIncluding":"9319.0","versionEndExcluding":"6.0.9319.885"},{"vulnerable":true,"criteria":"cpe:2.3:a:microsoft:skype_for_business_server_subscription_edition:*:cu1:*:*:*:*:*:*","versionStartIncluding":"2046.0","versionEndExcluding":"7.0.2046.879"},{"vulnerable":true,"criteria":"cpe:2.3:a:microsoft:skype_for_business_server_2019:*:cu8:*:*:*:*:*:*","versionStartIncluding":"2046.0","versionEndExcluding":"7.0.2046.569"}]}]}]}],"prioritization":[{"source":"CISA-ADP","type":"SSVC","role":"CISA Coordinator","timestamp":"2026-09-08T19:14:13.483335Z","decisions":[{"name":"Exploitation","value":"none"},{"name":"Automatable","value":"yes"},{"name":"Technical Impact","value":"partial"}]}]},"title":"Skype for Business and Lync Denial of Service Vulnerability","titleSource":"microsoft","descriptionSource":"microsoft","description":"Integer underflow (wrap or wraparound) in Skype for Business allows an unauthorized attacker to deny service over a network.","score":7.5,"severity":"high","published":"2026-09-08T18:39:44.434Z","modified":"2026-10-30T21:57:48.039Z","withdrawn":false,"knownExploited":false,"affected":[],"products":[{"vendor":"Microsoft","name":"Skype for Business Server 2015 CU13","platforms":["x64-based Systems"],"versions":[{"version":"9319.0","status":"affected","lessThan":"6.0.9319.885","versionType":"custom"}],"cpes":[],"source":"microsoft","url":"https://www.cve.org/CVERecord?id=CVE-2026-66307"},{"vendor":"Microsoft","name":"Skype for Business Server 2019 CU8","platforms":["x64-based Systems"],"versions":[{"version":"2046.0","status":"affected","lessThan":"7.0.2046.569","versionType":"custom"}],"cpes":[],"source":"microsoft","url":"https://www.cve.org/CVERecord?id=CVE-2026-66307"},{"vendor":"Microsoft","name":"Skype for Business Server Subscription Edition CU1","platforms":["x64-based Systems"],"versions":[{"version":"2046.0","status":"affected","lessThan":"7.0.2046.879","versionType":"custom"}],"cpes":[],"source":"microsoft","url":"https://www.cve.org/CVERecord?id=CVE-2026-66307"}],"remediation":[],"references":["https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-66307"],"sources":[{"name":"CVE","id":"CVE-2026-66307","modified":"2026-10-30T21:57:48.039Z","url":"https://www.cve.org/CVERecord?id=CVE-2026-66307"}],"assessments":[{"source":"microsoft","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C","score":7.5}],"sourceAffected":[],"observedAt":"2026-10-30T22:49:00.915Z","kev":{"status":"not-listed","checkedAt":"2026-10-31T14:00:31.626Z"},"coverage":[{"source":"NVD","status":"available","checkedAt":"2026-10-31T00:10:33.369Z","attemptedAt":"2026-10-31T00:10:33.369Z"},{"source":"GHSA","status":"available","checkedAt":"2026-10-31T00:10:31.877Z","attemptedAt":"2026-10-31T00:10:31.877Z"},{"source":"EUVD","status":"available","checkedAt":"2026-10-31T00:10:32.255Z","attemptedAt":"2026-10-31T00:10:32.255Z"},{"source":"EPSS","status":"available","checkedAt":"2026-10-31T00:10:32.670Z","attemptedAt":"2026-10-31T00:10:32.670Z"}],"evidence":[{"source":"GitHub Advisory Database","id":"GHSA-fmx2-865f-8c6j","url":"https://github.com/advisories/GHSA-fmx2-865f-8c6j","modified":"2026-09-08T21:34:26Z","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","checkedAt":"2026-10-31T00:10:31.877Z"},{"source":"ENISA EUVD","id":"EUVD-2026-73941","url":"https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-73941","modified":"Oct 30, 2026, 9:57:48 PM","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C","checkedAt":"2026-10-31T00:10:32.255Z"},{"source":"FIRST EPSS","id":"CVE-2026-66307","url":"https://www.first.org/epss/","probability":0.01174,"percentile":0.67495,"date":"2026-10-30","checkedAt":"2026-10-31T00:10:32.670Z"},{"source":"NVD","id":"CVE-2026-66307","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-66307","modified":"2026-09-16T19:24:44.230","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","checkedAt":"2026-10-31T00:10:33.369Z"}],"aiSummary":{"text":"Skype for Business has an integer underflow vulnerability, allowing an unauthorized attacker to deny service over a network, affecting versions 9319.0 to 6.0.9319.885, 2046.0 to 7.0.2046.569, and 2046.0 to 7.0.2046.879.","model":"@cf/meta/llama-3.3-70b-instruct-fp8-fast","generatedAt":"2026-10-31T00:26:07.628Z","sources":[{"name":"CVE","url":"https://www.cve.org/CVERecord?id=CVE-2026-66307"}]}}