{"id":"CVE-2021-21005","url":"https://www.cyber-defence.io/tools/cve/CVE-2021-21005","generatedAt":"2026-10-27T20:21:00.739Z","title":"In Phoenix Contact FL SWITCH SMCS series products in multiple versions if an attacker sends a hand-crafted TCP-Packet with the Urgent-Flag set and the Urgent-Pointer set to 0, the network stack will crash.","description":"In Phoenix Contact FL SWITCH SMCS series products in multiple versions if an attacker sends a hand-crafted TCP-Packet with the Urgent-Flag set and the Urgent-Pointer set to 0, the network stack will crash. The device needs to be rebooted afterwards.","published":"2021-06-25T19:15:09.000Z","lastModified":"2026-06-17T03:34:39.000Z","status":"Modified","sourceIdentifier":"info@cert.vde.com","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-362"],"affected":["phoenixcontact/fl switch smcs 16tx firmware","phoenixcontact/fl switch smcs 14tx\\/2fx firmware","phoenixcontact/fl switch smcs 14tx\\/2fx-sm firmware","phoenixcontact/fl switch smcs 8gt firmware","phoenixcontact/fl switch smcs 6gt\\/2sfp firmware","phoenixcontact/fl switch smcs 8tx-pn firmware","phoenixcontact/fl switch smcs 4tx-pn firmware","phoenixcontact/fl switch smcs 8tx firmware","phoenixcontact/fl switch smcs 6tx\\/2sfp firmware","phoenixcontact/fl switch smn 6tx\\/2pof-pn firmware","phoenixcontact/fl switch smn 8tx-pn firmware","phoenixcontact/fl switch smn 6tx\\/2fx firmware","phoenixcontact/fl switch smn 6tx\\/2fx sm firmware","phoenixcontact/fl nat smn 8tx firmware","phoenixcontact/fl nat smn 8tx-m firmware"],"epss":{"score":0.00678,"percentile":0.52063,"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 (0.68%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit."},"changes":[],"references":[{"url":"https://cert.vde.com/en-us/advisories/vde-2021-023","tags":["Third Party Advisory"],"source":"info@cert.vde.com"},{"url":"https://cert.vde.com/en-us/advisories/vde-2021-023","tags":["Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2021-21005","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."}