{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-21921","assignerOrgId":"8cbe9d5a-a066-4c94-8978-4b15efeae968","state":"PUBLISHED","assignerShortName":"juniper","dateReserved":"2026-01-05T17:32:48.712Z","datePublished":"2026-01-15T20:28:29.656Z","dateUpdated":"2026-01-15T20:55:25.182Z"},"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Junos OS","vendor":"Juniper Networks","versions":[{"lessThan":"22.4R3-S8","status":"affected","version":"0","versionType":"semver"},{"lessThan":"23.2R2-S5","status":"affected","version":"23.2","versionType":"semver"},{"lessThan":"23.4R2","status":"affected","version":"23.4","versionType":"semver"}]},{"defaultStatus":"unaffected","product":"Junos OS Evolved","vendor":"Juniper Networks","versions":[{"lessThan":"22.4R3-S8-EVO","status":"affected","version":"0","versionType":"semver"},{"lessThan":"23.2R2-S5-EVO","status":"affected","version":"23.2","versionType":"semver"},{"lessThan":"23.4R2-EVO","status":"affected","version":"23.4","versionType":"semver"}]}],"configurations":[{"lang":"en","supportingMedia":[{"base64":false,"type":"text/html","value":"A device is only exposed to this issue if GRPC services are configured:

[ system services extension-service request-response grpc ]\n\n
"}],"value":"A device is only exposed to this issue if GRPC services are configured:\n\n[ system services extension-service request-response grpc ]"}],"datePublic":"2026-01-14T17:00:00.000Z","descriptions":[{"lang":"en","supportingMedia":[{"base64":false,"type":"text/html","value":"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).

When 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.

This issue affects:

 Junos OS: 

Junos OS Evolved:

"}],"value":"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."}],"exploits":[{"lang":"en","supportingMedia":[{"base64":false,"type":"text/html","value":"Juniper SIRT is not aware of any malicious exploitation of this vulnerability."}],"value":"Juniper SIRT is not aware of any malicious exploitation of this vulnerability."}],"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"HIGH","baseScore":6.5,"baseSeverity":"MEDIUM","confidentialityImpact":"NONE","integrityImpact":"NONE","privilegesRequired":"LOW","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","version":"3.1"},"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}]},{"cvssV4_0":{"Automatable":"YES","Recovery":"AUTOMATIC","Safety":"NOT_DEFINED","attackComplexity":"LOW","attackRequirements":"NONE","attackVector":"NETWORK","baseScore":7.1,"baseSeverity":"HIGH","privilegesRequired":"LOW","providerUrgency":"NOT_DEFINED","subAvailabilityImpact":"LOW","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","userInteraction":"NONE","valueDensity":"NOT_DEFINED","vectorString":"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","version":"4.0","vulnAvailabilityImpact":"HIGH","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"NONE","vulnerabilityResponseEffort":"MODERATE"},"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}]}],"problemTypes":[{"descriptions":[{"cweId":"CWE-416","description":"CWE-416 Use After Free","lang":"en","type":"CWE"}]}],"providerMetadata":{"orgId":"8cbe9d5a-a066-4c94-8978-4b15efeae968","shortName":"juniper","dateUpdated":"2026-01-15T20:28:29.656Z"},"references":[{"tags":["vendor-advisory"],"url":"https://supportportal.juniper.net/JSA106021"},{"tags":["vendor-advisory"],"url":"https://kb.juniper.net/JSA106021"}],"solutions":[{"lang":"en","supportingMedia":[{"base64":false,"type":"text/html","value":"The following software releases have been updated to resolve this specific issue:
Junos OS Evolved: 22.4R3-S8-EVO, 23.2R2-S5-EVO, 23.4R2-EVO, 24.2R1-EVO, and all subsequent releases;
Junos OS: 22.4R3-S8, 23.2R2-S5, 23.4R2, 24.2R1, and all subsequent releases."}],"value":"The following software releases have been updated to resolve this specific issue:\nJunos OS Evolved: 22.4R3-S8-EVO, 23.2R2-S5-EVO, 23.4R2-EVO, 24.2R1-EVO, and all subsequent releases;\nJunos OS: 22.4R3-S8, 23.2R2-S5, 23.4R2, 24.2R1, and all subsequent releases."}],"source":{"advisory":"JSA106021","defect":["1791928"],"discovery":"INTERNAL"},"title":"Junos OS and Junos OS Evolved: When telemetry collectors are frequently subscribing and unsubscribing to sensors chassisd or rpd will crash","workarounds":[{"lang":"en","supportingMedia":[{"base64":false,"type":"text/html","value":"There are no known workarounds for this issue."}],"value":"There are no known workarounds for this issue."}],"x_generator":{"engine":"Vulnogram 0.1.0-dev"}},"adp":[{"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-01-15T20:54:58.001808Z","id":"CVE-2026-21921","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"title":"CISA ADP Vulnrichment","providerMetadata":{"orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP","dateUpdated":"2026-01-15T20:55:25.182Z"}}]}}