{"id":"CVE-2026-66307","aliases":["EUVD-2026-73941","GHSA-fmx2-865f-8c6j"],"status":"published","title":"Skype for Business and Lync Denial of Service Vulnerability","description":"Integer underflow (wrap or wraparound) in Skype for Business allows an unauthorized attacker to deny service over a network.","severity":{"version":"3.1","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","level":"high","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-10","score":0.01174,"percentile":0.6778,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-191"],"published":"2026-09-08T18:39:44Z","modified":"2026-11-10T21:38:33Z","products":[{"vendor":"microsoft","product":"skype for business server 2015 cu13"},{"vendor":"microsoft","product":"skype for business server 2019 cu8"},{"vendor":"microsoft","product":"skype for business server subscription edition cu1"},{"vendor":"microsoft","product":"skype_for_business_server"},{"vendor":"microsoft","product":"skype_for_business_server_subscription_edition"}],"references":[{"url":"https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-66307","tags":["vendor-advisory","patch","Patch","Vendor Advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-66307"},{"url":"https://github.com/advisories/GHSA-fmx2-865f-8c6j"}],"sources":{"cve":[{"id":"CVE-2026-66307","title":"Skype for Business and Lync Denial of Service Vulnerability","description":"Integer underflow (wrap or wraparound) in Skype for Business allows an unauthorized attacker to deny service over a network.","status":"published","published":"2026-09-08T18:39:44.434Z","modified":"2026-11-10T21:38:33.891Z","cvss":[{"version":"3.1","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","level":"high","assessor":"cna"}],"cwes":["CWE-191"],"updated_at":"2026-11-10T22:48:52.144232Z"}],"euvd":[{"id":"EUVD-2026-73941","description":"Integer underflow (wrap or wraparound) in Skype for Business allows an unauthorized attacker to deny service over a network.","status":"published","published":"2026-09-08T18:39:44Z","modified":"2026-11-10T21:38:33Z","cvss":[{"version":"3.1","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","level":"high"}],"updated_at":"2026-11-10T23:24:18.784503Z"}],"ghsa":[{"id":"GHSA-fmx2-865f-8c6j","title":"Integer underflow (wrap or wraparound) in Skype for Business allows an unauthorized attacker to...","description":"Integer underflow (wrap or wraparound) in Skype for Business allows an unauthorized attacker to deny service over a network.","status":"published","published":"2026-09-08T21:34:17Z","modified":"2026-09-08T21:34:26Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high"}],"cwes":["CWE-191"],"updated_at":"2026-11-02T15:11:35.275364Z"}],"nvd":[{"id":"CVE-2026-66307","description":"Integer underflow (wrap or wraparound) in Skype for Business allows an unauthorized attacker to deny service over a network.","status":"published","published":"2026-09-08T19:18:08.327Z","modified":"2026-09-16T19:24:44.23Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high","assessor":"secondary"}],"cwes":["CWE-191"],"updated_at":"2026-11-02T14:12:45.264578Z"}]}}