{"id":"CVE-2020-35684","url":"https://www.cyber-defence.io/tools/cve/CVE-2020-35684","generatedAt":"2026-10-28T06:49:33.679Z","title":"When the IP payload size is set to be smaller than the size of the IP header, the TCP checksum computation function may read out of bounds (a low-impact write-out-of-bounds is also possible).","description":"An issue was discovered in HCC Nichestack 3.0. The code that parses TCP packets relies on an unchecked value of the IP payload size (extracted from the IP header) to compute the length of the TCP payload within the TCP checksum computation function. When the IP payload size is set to be smaller than the size of the IP header, the TCP checksum computation function may read out of bounds (a low-impact write-out-of-bounds is also possible).","published":"2021-08-19T12:15:08.000Z","lastModified":"2026-06-17T03:14:08.000Z","status":"Modified","sourceIdentifier":"cve@mitre.org","cvss":{"version":"3.1","score":7.5,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"},"cwe":["CWE-20"],"affected":["hcc-embedded/nichestack","siemens/sentron 3wl com35 firmware","siemens/sentron 3wa com190 firmware"],"epss":{"score":0.02287,"percentile":0.83093,"date":"2026-10-27","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 (2.29%). 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/pdf/ssa-789208.pdf","tags":["Mitigation","Third Party Advisory"],"source":"cve@mitre.org"},{"url":"https://www.forescout.com/blog/new-critical-operational-technology-vulnerabilities-found-on-nichestack/","tags":["Mitigation","Third Party Advisory"],"source":"cve@mitre.org"},{"url":"https://www.hcc-embedded.com","tags":["Product"],"source":"cve@mitre.org"},{"url":"https://www.kb.cert.org/vuls/id/608209","tags":["Third Party Advisory","US Government Resource"],"source":"cve@mitre.org"},{"url":"https://cert-portal.siemens.com/productcert/pdf/ssa-789208.pdf","tags":["Mitigation","Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://www.forescout.com/blog/new-critical-operational-technology-vulnerabilities-found-on-nichestack/","tags":["Mitigation","Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://www.hcc-embedded.com","tags":["Product"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://www.kb.cert.org/vuls/id/608209","tags":["Third Party Advisory","US Government Resource"],"source":"af854a3a-2127-422b-91ae-364da2661108"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2020-35684","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."}