{"id":"CVE-2021-27393","url":"https://www.cyber-defence.io/tools/cve/CVE-2021-27393","generatedAt":"2026-10-27T22:28:02.515Z","title":"A vulnerability has been identified in Nucleus NET (All versions), Nucleus ReadyStart V3 (All versions < V2013.08), Nucleus Source Code (Versions including affected DNS modules).","description":"A vulnerability has been identified in Nucleus NET (All versions), Nucleus ReadyStart V3 (All versions < V2013.08), Nucleus Source Code (Versions including affected DNS modules). The DNS client does not properly randomize UDP port numbers of DNS requests. That could allow an attacker to poison the DNS cache or spoof DNS resolving.","published":"2021-04-22T21:15:10.000Z","lastModified":"2026-06-17T03:44:47.000Z","status":"Modified","sourceIdentifier":"productcert@siemens.com","cvss":{"version":"3.1","score":5.3,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N"},"cwe":["CWE-330"],"affected":["siemens/nucleus net","siemens/nucleus readystart v3","siemens/nucleus source code"],"epss":{"score":0.00751,"percentile":0.54731,"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":"low","text":"Lower severity and a low EPSS score (0.75%). Track it; it rarely justifies an emergency change on its own."},"changes":[],"references":[{"url":"https://cert-portal.siemens.com/productcert/pdf/ssa-201384.pdf","tags":["Vendor Advisory"],"source":"productcert@siemens.com"},{"url":"https://cert-portal.siemens.com/productcert/pdf/ssa-201384.pdf","tags":["Vendor Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2021-27393","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."}