CVE-2026-21903

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"CVE-2026-21903", "options": [{"exploitation": "none"}, {"automatable": "no"}, {"technicalImpact": "partial"}], "role": "CISA Coordinator", "timestamp": "2026-01-15T21:12:00.833031Z", "version": "2.0.3"}}]}, "published": "2026-01-15T21:16:05.807", "references": [{"source": "sirt@juniper.net", "tags": ["Vendor Advisory"], "url": "https://kb.juniper.net/JSA106022"}, {"source": "sirt@juniper.net", "tags": ["Vendor Advisory"], "url": "https://supportportal.juniper.net/JSA106022"}], "sourceIdentifier": "sirt@juniper.net", "vulnStatus": "Analyzed", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-121"}], "source": "sirt@juniper.net", "type": "Secondary"}]}

{}

{"analysis": {"en": {"generated_at": "2026-04-18T16:09:03.075382+00:00", "value": {"mitigation_remediation": ["Apply the latest Junos OS releases that contain the fix\u201422.4R3\u2011S7, 23.2R2\u2011S4, 23.4R2, 24.2R1, or later\u2014to all affected devices", "Limit or disable telemetry sensor subscriptions until all devices are patched to mitigate the denial\u2011of\u2011service risk", "Configure access controls so that only authorized high\u2011privilege users can subscribe to telemetry sensors at scale."], "summary": {"action": "Apply Patch", "impact": "Denial of Service caused by a stack\u2011based buffer overflow that crashes all packet forwarding engine connections when telemetry sensors are subscribed at scale"}, "threat_synthesis": {"affected_systems": "The vulnerability affects Juniper Networks Junos OS, specifically all releases before 22.4R3\u2011S7, before 23.2R2\u2011S4, and before 23.4R2. Devices running those versions are susceptible to the crash when they subscribe to telemetry sensors.", "description_and_impact": "A stack\u2011based buffer overflow exists in the Packet Forwarding Engine of Junos OS. When an attacker subscribes to telemetry sensors at a large scale, all FPC connections drop, the FPC crashes, and the device restarts, resulting in a denial\u2011of\u2011service condition. The problem is triggered by low\u2011privilege, network\u2011based attackers and does not grant code execution, but it can disrupt network services.", "risk_and_exploitability": "The CVSS score of 7.1 indicates moderate severity, while the EPSS score of less than\u00a01\u202f% shows a very low probability of exploitation at the current time. The issue is not listed in the CISA Known Exploited Vulnerabilities catalog, and no workaround exists. The likely attack vector is inferred to be network\u2011based through the subscription of telemetry sensors, and an attacker only needs low\u2011privilege access to trigger the denial of service."}}}}, "created": "2026-01-16T13:42:58.761289+00:00", "updated": "2026-04-18T16:15:04.603582+00:00", "vendors": ["juniper_networks", "juniper_networks$PRODUCT$junos_os"]}