{"api_version":"1","generated_at":"2026-07-23T13:39:55+00:00","cve":"CVE-2021-0239","urls":{"html":"https://cve.report/CVE-2021-0239","api":"https://cve.report/api/cve/CVE-2021-0239.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2021-0239","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2021-0239"},"summary":{"title":"CVE-2021-0239","description":"In Juniper Networks Junos OS Evolved, receipt of a stream of specific genuine Layer 2 frames may cause the Advanced Forwarding Toolkit (AFT) manager process (Evo-aftmand), responsible for handling Route, Class-of-Service (CoS), Firewall operations within the packet forwarding engine (PFE) to crash and restart, leading to a Denial of Service (DoS) condition. By continuously sending this specific stream of genuine Layer 2 frames, an attacker can repeatedly crash the PFE, causing a sustained Denial of Service (DoS). This issue affects Juniper Networks Junos OS Evolved: All versions prior to 20.4R1-EVO. 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