{"id":"CVE-2026-21921","aliases":["EUVD-2026-2693","GHSA-fm5x-5pxq-6229"],"status":"published","title":"Junos OS and Junos OS Evolved: When telemetry collectors are frequently subscribing and unsubscribing to sensors chassisd or rpd will crash","description":"A Use After Free vulnerability in the chassis daemon (chassisd) of Juniper Networks Junos OS and Junos OS Evolved allows a network-based attacker authenticated with low privileges to cause a Denial-of-Service (DoS).\n\nWhen telemetry collectors are frequently subscribing and unsubscribing to sensors continuously over a long period of time, telemetry-capable processes like chassisd, rpd or mib2d will crash and restart, which - depending on the process - can cause a complete outage until the system has recovered.\n\nThis issue affects:\n\n Junos OS: \n\n\n\n  *  all versions before 22.4R3-S8,\n  *  23.2 versions before 23.2R2-S5,\n  *  23.4 versions before 23.4R2;\n\n\n\n\nJunos OS Evolved:\n\n\n\n  *  all versions before 22.4R3-S8-EVO,\n  *  23.2 versions before 23.2R2-S5-EVO,\n  *  23.4 versions before 23.4R2-EVO.","severity":{"version":"4.0","score":7.1,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L/AU:Y/R:A/RE:M","level":"high","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-12","score":0.00372,"percentile":0.31552,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-416"],"published":"2026-01-15T20:28:29Z","modified":"2026-06-17T10:19:10Z","products":[{"vendor":"juniper","product":"junos"},{"vendor":"juniper","product":"junos_os_evolved"},{"vendor":"juniper networks","product":"junos os"},{"vendor":"juniper networks","product":"junos os evolved"}],"references":[{"url":"https://supportportal.juniper.net/JSA106021","tags":["vendor-advisory","Vendor Advisory"]},{"url":"https://kb.juniper.net/JSA106021","tags":["vendor-advisory","Vendor Advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-21921"},{"url":"https://github.com/advisories/GHSA-fm5x-5pxq-6229"}],"sources":{"cve":[{"id":"CVE-2026-21921","title":"Junos OS and Junos OS Evolved: When telemetry collectors are frequently subscribing and unsubscribing to sensors chassisd or rpd will crash","description":"A Use After Free vulnerability in the chassis daemon (chassisd) of Juniper Networks Junos OS and Junos OS Evolved allows a network-based attacker authenticated with low privileges to cause a Denial-of-Service (DoS).\n\nWhen telemetry collectors are frequently subscribing and unsubscribing to sensors continuously over a long period of time, telemetry-capable processes like chassisd, rpd or mib2d will crash and restart, which - depending on the process - can cause a complete outage until the system has recovered.\n\nThis issue affects:\n\n Junos OS: \n\n\n\n  *  all versions before 22.4R3-S8,\n  *  23.2 versions before 23.2R2-S5,\n  *  23.4 versions before 23.4R2;\n\n\n\n\nJunos OS Evolved:\n\n\n\n  *  all versions before 22.4R3-S8-EVO,\n  *  23.2 versions before 23.2R2-S5-EVO,\n  *  23.4 versions before 23.4R2-EVO.","status":"published","published":"2026-01-15T20:28:29.656Z","modified":"2026-01-15T20:55:25.182Z","cvss":[{"version":"4.0","score":7.1,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L/AU:Y/R:A/RE:M","level":"high","assessor":"cna"},{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","level":"medium","assessor":"cna"}],"cwes":["CWE-416"],"updated_at":"2026-11-02T13:41:53.237769Z"}],"euvd":[{"id":"EUVD-2026-2693","description":"A Use After Free vulnerability in the chassis daemon (chassisd) of Juniper Networks Junos OS and Junos OS Evolved allows a network-based attacker authenticated with low privileges to cause a Denial-of-Service (DoS).\n\nWhen telemetry collectors are frequently subscribing and unsubscribing to sensors continuously over a long period of time, telemetry-capable processes like chassisd, rpd or mib2d will crash and restart, which - depending on the process - can cause a complete outage until the system has recovered.\n\nThis issue affects:\n\n Junos OS: \n\n\n\n  *  all versions before 22.4R3-S8,\n  *  23.2 versions before 23.2R2-S5,\n  *  23.4 versions before 23.4R2;\n\n\n\n\nJunos OS Evolved:\n\n\n\n  *  all versions before 22.4R3-S8-EVO,\n  *  23.2 versions before 23.2R2-S5-EVO,\n  *  23.4 versions before 23.4R2-EVO.","status":"published","published":"2026-01-15T20:28:29Z","modified":"2026-01-15T20:55:25Z","cvss":[{"version":"4.0","score":7.1,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L/AU:Y/R:A/RE:M","level":"high"}],"updated_at":"2026-11-02T19:48:51.36047Z"}],"ghsa":[{"id":"GHSA-fm5x-5pxq-6229","title":"A Use After Free vulnerability in the chassis daemon (chassisd) of Juniper Networks Junos OS and...","description":"A Use After Free vulnerability in the chassis daemon (chassisd) of Juniper Networks Junos OS and Junos OS Evolved allows a network-based attacker authenticated with low privileges to cause a Denial-of-Service (DoS).\n\nWhen telemetry collectors are frequently subscribing and unsubscribing to sensors continuously over a long period of time, telemetry-capable processes like chassisd, rpd or mib2d will crash and restart, which - depending on the process - can cause a complete outage until the system has recovered.\n\nThis issue affects:\n\n Junos OS: \n\n\n\n  *  all versions before 22.4R3-S8,\n  *  23.2 versions before 23.2R2-S5,\n  *  23.4 versions before 23.4R2;\n\n\n\n\nJunos OS Evolved:\n\n\n\n  *  all versions before 22.4R3-S8-EVO,\n  *  23.2 versions before 23.2R2-S5-EVO,\n  *  23.4 versions before 23.4R2-EVO.","status":"published","published":"2026-01-15T21:31:48Z","modified":"2026-01-15T21:31:56Z","cvss":[{"version":"4.0","score":7.1,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:Y/R:A/V:X/RE:M/U:X","level":"high"},{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","level":"medium"}],"cwes":["CWE-416"],"updated_at":"2026-11-02T15:05:38.149378Z"}],"nvd":[{"id":"CVE-2026-21921","description":"A Use After Free vulnerability in the chassis daemon (chassisd) of Juniper Networks Junos OS and Junos OS Evolved allows a network-based attacker authenticated with low privileges to cause a Denial-of-Service (DoS).\n\nWhen telemetry collectors are frequently subscribing and unsubscribing to sensors continuously over a long period of time, telemetry-capable processes like chassisd, rpd or mib2d will crash and restart, which - depending on the process - can cause a complete outage until the system has recovered.\n\nThis issue affects:\n\n Junos OS: \n\n\n\n  *  all versions before 22.4R3-S8,\n  *  23.2 versions before 23.2R2-S5,\n  *  23.4 versions before 23.4R2;\n\n\n\n\nJunos OS Evolved:\n\n\n\n  *  all versions before 22.4R3-S8-EVO,\n  *  23.2 versions before 23.2R2-S5-EVO,\n  *  23.4 versions before 23.4R2-EVO.","status":"published","published":"2026-01-15T21:16:08.4Z","modified":"2026-06-17T10:19:10.153Z","cvss":[{"version":"4.0","score":7.1,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:Y/R:A/V:X/RE:M/U:X","level":"high","assessor":"secondary"},{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","level":"medium","assessor":"secondary"}],"cwes":["CWE-416"],"updated_at":"2026-11-02T14:12:04.066712Z"}]}}