{"id":"CVE-2026-20221","url":"https://www.cyber-defence.io/tools/cve/CVE-2026-20221","generatedAt":"2026-10-28T01:52:06.324Z","title":"Multiple Cisco products are affected by a vulnerability in the generic routing encapsulation (GRE) tunnel decapsulation feature of the Snort 3 Detection Engine that could allow an unauthenticated, remote attacker to cause an unexpected restart of the…","description":"Multiple Cisco products are affected by a vulnerability in the generic routing encapsulation (GRE) tunnel decapsulation feature of the Snort 3 Detection Engine that could allow an unauthenticated, remote attacker to cause an unexpected restart of the Snort 3 Detection Engine.\r\n\r\nThis vulnerability is due to improper handling of nested GRE traffic. An attacker could exploit this vulnerability by sending a crafted GRE payload through an affected device. A successful exploit could allow the attacker to trigger an unexpected reload of the Snort 3 Detection Engine, resulting in either a bypass or denial of service (DoS) condition, depending on device configuration. For more information, see the  section of this advisory. The Snort 3 Detection Engine will restart automatically. No manual intervention is required.","published":"2026-10-21T17:18:28.000Z","lastModified":"2026-10-22T14:17:41.000Z","status":"Awaiting Analysis","sourceIdentifier":"psirt@cisco.com","cvss":{"version":"3.1","score":5.8,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L"},"cwe":["CWE-476"],"affected":[],"epss":{"score":0.00577,"percentile":0.47281,"date":"2026-10-26","history":[{"date":"2026-10-22","score":0.00454,"percentile":0.38423}]},"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 (0.58%). Track it; it rarely justifies an emergency change on its own."},"changes":[{"kind":"new","label":"New CVE","at":"2026-10-21T17:18:28.000Z","detail":{"score":"5.8","severity":"MEDIUM","publishedAt":"2026-10-21T17:18:27.947Z"},"summary":"New CVE, medium severity (CVSS 5.8)."}],"references":[{"url":"https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-snort3-gre-JNpMHrTv","source":"psirt@cisco.com"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-20221","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."}