{"id":"CVE-2026-21903","state":"PUBLISHED","title":"Junos OS: Subscribing to telemetry sensors at scale causes all FPCs to crash","description":"A Stack-based Buffer Overflow vulnerability in the Packet Forwarding Engine (pfe) of Juniper Networks Junos OS allows a network-based attacker, authenticated with low privileges to cause a Denial-of-Service (DoS).\n\n\n\nSubscribing to telemetry sensors at scale causes all FPC connections to drop, resulting in an FPC crash and restart.\nThe issue was not seen when YANG packages for the specific sensors were installed. \n\n\n\nThis issue affects Junos OS: \n\n\n\n  *  all versions before 22.4R3-S7,\n  *  23.2 version before 23.2R2-S4,\n  *  23.4 versions before 23.4R2.","publishedAt":"2026-01-15T20:18:36.767Z","updatedAt":"2026-01-15T21:12:08.631Z","severity":{"score":7.1,"label":"High","version":"4.0","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","source":"juniper"},"assigner":"juniper","products":["Juniper Networks Junos OS"],"affected":[{"vendor":"Juniper Networks","product":"Junos OS","defaultStatus":"unaffected","versions":[{"version":"0","status":"affected","lessThan":"22.4R3-S7","versionType":"semver"},{"version":"23.2","status":"affected","lessThan":"23.2R2-S4","versionType":"semver"},{"version":"23.4","status":"affected","lessThan":"23.4R2","versionType":"semver"}]}],"references":["https://supportportal.juniper.net/JSA106022","https://kb.juniper.net/JSA106022"],"weaknesses":["CWE-121"],"ingestedAt":"2026-10-29T20:11:10.572Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/21xxx/CVE-2026-21903.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-21903","state":"PUBLISHED","datePublished":"2026-01-15T20:18:36.767Z","dateUpdated":"2026-01-15T21:12:08.631Z","assignerShortName":"juniper","assignerOrgId":"8cbe9d5a-a066-4c94-8978-4b15efeae968","dateReserved":"2026-01-05T17:32:48.709Z"},"containers":{"cna":{"title":"Junos OS: Subscribing to telemetry sensors at scale causes all FPCs to crash","descriptions":[{"lang":"en","value":"A Stack-based Buffer Overflow vulnerability in the Packet Forwarding Engine (pfe) of Juniper Networks Junos OS allows a network-based attacker, authenticated with low privileges to cause a Denial-of-Service (DoS).\n\n\n\nSubscribing to telemetry sensors at scale causes all FPC connections to drop, resulting in an FPC crash and restart.\nThe issue was not seen when YANG packages for the specific sensors were installed. \n\n\n\nThis issue affects Junos OS: \n\n\n\n  *  all versions before 22.4R3-S7,\n  *  23.2 version before 23.2R2-S4,\n  *  23.4 versions before 23.4R2."}],"affected":[{"vendor":"Juniper Networks","product":"Junos OS","defaultStatus":"unaffected","versions":[{"version":"0","status":"affected","lessThan":"22.4R3-S7","versionType":"semver"},{"version":"23.2","status":"affected","lessThan":"23.2R2-S4","versionType":"semver"},{"version":"23.4","status":"affected","lessThan":"23.4R2","versionType":"semver"}]}],"references":[{"url":"https://supportportal.juniper.net/JSA106022","tags":["vendor-advisory"]},{"url":"https://kb.juniper.net/JSA106022","tags":["vendor-advisory"]}],"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":"NOT_DEFINED","Recovery":"NOT_DEFINED","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","version":"4.0","vulnAvailabilityImpact":"HIGH","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"NONE","vulnerabilityResponseEffort":"NOT_DEFINED"},"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}]}],"problemTypes":[{"descriptions":[{"cweId":"CWE-121","description":"CWE-121 Stack-based Buffer Overflow","lang":"en","type":"CWE"}]}],"providerMetadata":{"shortName":"juniper","orgId":"8cbe9d5a-a066-4c94-8978-4b15efeae968","dateUpdated":"2026-01-15T20:18:36.767Z"},"configurations":[{"lang":"en","supportingMedia":[{"base64":false,"type":"text/html","value":"A device is only exposed to this issue if GRPC services are configured:<br><br><tt>[ system services extension-service request-response grpc ]</tt>"}],"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","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."}],"solutions":[{"lang":"en","supportingMedia":[{"base64":false,"type":"text/html","value":"The following software releases have been updated to resolve this specific issue: 22.4R3-S7, 23.2R2-S4, 23.4R2, 24.2R1, and all subsequent releases."}],"value":"The following software releases have been updated to resolve this specific issue: 22.4R3-S7, 23.2R2-S4, 23.4R2, 24.2R1, and all subsequent releases."}],"source":{"advisory":"JSA106022","defect":["1811989"],"discovery":"INTERNAL"},"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":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-01-15T21:12:00.833031Z","id":"CVE-2026-21903","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-01-15T21:12:08.631Z"}}]}}}