{"id":"CVE-2021-37186","url":"https://www.cyber-defence.io/tools/cve/CVE-2021-37186","generatedAt":"2026-10-27T20:54:30.938Z","title":"A vulnerability has been identified in LOGO!","description":"A vulnerability has been identified in LOGO! CMR2020 (All versions < V2.2), LOGO! CMR2040 (All versions < V2.2), SIMATIC RTU3010C (All versions < V4.0.9), SIMATIC RTU3030C (All versions < V4.0.9), SIMATIC RTU3031C (All versions < V4.0.9), SIMATIC RTU3041C (All versions < V4.0.9). The underlying TCP/IP stack does not properly calculate the random numbers used as ISN (Initial Sequence Numbers). An adjacent attacker with network access to the LAN interface could interfere with traffic, spoof the connection and gain access to sensitive information.","published":"2021-09-14T11:15:26.000Z","lastModified":"2026-06-17T04:00:13.000Z","status":"Modified","sourceIdentifier":"productcert@siemens.com","cvss":{"version":"3.1","score":5.4,"severity":"MEDIUM","vector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N"},"cwe":["CWE-330"],"affected":["siemens/logo\\! cmr2020 firmware","siemens/logo\\! cmr2040 firmware","siemens/simatic rtu3010c firmware","siemens/simatic rtu3030c firmware","siemens/simatic rtu3031c firmware","siemens/simatic rtu3041c firmware"],"epss":{"score":0.00356,"percentile":0.29101,"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 (0.36%). Track it; it rarely justifies an emergency change on its own."},"changes":[],"references":[{"url":"https://cert-portal.siemens.com/productcert/pdf/ssa-316383.pdf","tags":["Patch","Vendor Advisory"],"source":"productcert@siemens.com"},{"url":"https://cert-portal.siemens.com/productcert/pdf/ssa-316383.pdf","tags":["Patch","Vendor Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2021-37186","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."}