{"id":"CVE-2021-25664","url":"https://www.cyber-defence.io/tools/cve/CVE-2021-25664","generatedAt":"2026-10-27T21:19:10.894Z","title":"A vulnerability has been identified in Capital Embedded AR Classic 431-422 (All versions), Capital Embedded AR Classic R20-11 (All versions < V2303), Nucleus NET (All versions), Nucleus ReadyStart V3 (All versions < V2017.02.4), Nucleus ReadyStart V4…","description":"A vulnerability has been identified in Capital Embedded AR Classic 431-422 (All versions), Capital Embedded AR Classic R20-11 (All versions < V2303), Nucleus NET (All versions), Nucleus ReadyStart V3 (All versions < V2017.02.4), Nucleus ReadyStart V4 (All versions < V4.1.0), Nucleus Source Code (All versions including affected IPv6 stack). The function that processes the Hop-by-Hop extension header in IPv6 packets and its options lacks any checks against the length field of the header, allowing attackers to put the function into an infinite loop by supplying arbitrary length values.","published":"2021-04-22T21:15:10.000Z","lastModified":"2026-06-17T03:42:19.000Z","status":"Modified","sourceIdentifier":"productcert@siemens.com","cvss":{"version":"4.0","score":8.7,"severity":"HIGH","vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/M"},"cwe":["CWE-835"],"affected":["siemens/capital vstar","siemens/nucleus net","siemens/nucleus readystart v3","siemens/nucleus readystart v4","siemens/nucleus source code"],"epss":{"score":0.01885,"percentile":0.79352,"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 (1.88%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit."},"changes":[],"references":[{"url":"https://cert-portal.siemens.com/productcert/html/ssa-248289.html","source":"productcert@siemens.com"},{"url":"https://cert-portal.siemens.com/productcert/pdf/ssa-248289.pdf","tags":["Vendor Advisory"],"source":"productcert@siemens.com"},{"url":"https://us-cert.cisa.gov/ics/advisories/icsa-21-103-05","tags":["Third Party Advisory","US Government Resource"],"source":"productcert@siemens.com"},{"url":"https://cert-portal.siemens.com/productcert/html/ssa-248289.html","source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://cert-portal.siemens.com/productcert/pdf/ssa-248289.pdf","tags":["Vendor Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://us-cert.cisa.gov/ics/advisories/icsa-21-103-05","tags":["Third Party Advisory","US Government Resource"],"source":"af854a3a-2127-422b-91ae-364da2661108"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2021-25664","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."}