{"id":"CVE-2021-0239","aliases":["EUVD-2021-2858","GHSA-hr3q-mvqf-hmmc"],"status":"published","title":"Junos OS Evolved: Denial of Service due to receipt of specific genuine layer 2 frames.","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. This issue does not affect Junos OS versions.","severity":{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-08","score":0.00381,"percentile":0.32345,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-754"],"published":"2021-04-22T19:37:05Z","modified":"2026-06-17T03:29:34Z","products":[{"vendor":"juniper","product":"junos_os_evolved"},{"vendor":"juniper networks","product":"junos os evolved"}],"references":[{"url":"https://kb.juniper.net/JSA11134","tags":["x_refsource_MISC","x_transferred","Vendor Advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2021-0239"},{"url":"https://github.com/advisories/GHSA-hr3q-mvqf-hmmc"}],"sources":{"cve":[{"id":"CVE-2021-0239","title":"Junos OS Evolved: Denial of Service due to receipt of specific genuine layer 2 frames.","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. This issue does not affect Junos OS versions.","status":"published","published":"2021-04-22T19:37:05.415Z","modified":"2024-09-16T17:49:30.356Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"medium","assessor":"cna"}],"cwes":["CWE-754"],"updated_at":"2026-11-02T14:33:10.887946Z"}],"euvd":[{"id":"EUVD-2021-2858","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. This issue does not affect Junos OS versions.","status":"published","published":"2021-04-22T19:37:05Z","modified":"2024-09-16T17:49:30Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"medium"}],"updated_at":"2026-11-03T00:55:38.288771Z"}],"ghsa":[{"id":"GHSA-hr3q-mvqf-hmmc","title":"In Juniper Networks Junos OS Evolved, receipt of a stream of specific genuine Layer 2 frames may...","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. This issue does not affect Junos OS versions.","status":"published","published":"2022-05-24T17:48:12Z","modified":"2023-01-29T05:06:01Z","cwes":["CWE-754"],"updated_at":"2026-11-02T14:45:55.677123Z"}],"nvd":[{"id":"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. This issue does not affect Junos OS versions.","status":"published","published":"2021-04-22T20:15:08.943Z","modified":"2026-06-17T03:29:34.513Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"medium","assessor":"secondary"},{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"medium","assessor":"primary"},{"version":"2.0","score":6.1,"vector":"AV:A/AC:L/Au:N/C:N/I:N/A:C","level":"medium","assessor":"primary"}],"cwes":["CWE-754"],"updated_at":"2026-11-02T14:06:52.03307Z"}]}}