CVE-2026-21909
MEDIUMCVSS Vector
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Lifecycle Timeline
2Description
A Missing Release of Memory after Effective Lifetime vulnerability in the routing protocol daemon (rpd) Juniper Networks Junos OS and Junos OS Evolved allows an unauthenticated attacker controlling an adjacent IS-IS neighbor to send a specific update packet causing a memory leak. Continued receipt and processing of these packets will exhaust all available memory, crashing rpd and creating a Denial of Service (DoS) condition. Memory usage can be monitored through the use of the 'show task memory detail' command. For example: user@junos> show task memory detail | match ted-infra TED-INFRA-COOKIE 25 1072 28 1184 229 user@junos> show task memory detail | match ted-infra TED-INFRA-COOKIE 31 1360 34 1472 307 This issue affects: Junos OS: * from 23.2 before 23.2R2, * from 23.4 before 23.4R1-S2, 23.4R2, * from 24.1 before 24.1R2; Junos OS Evolved: * from 23.2 before 23.2R2-EVO, * from 23.4 before 23.4R1-S2-EVO, 23.4R2-EVO, * from 24.1 before 24.1R2-EVO. This issue does not affect Junos OS versions before 23.2R1 or Junos OS Evolved versions before 23.2R1-EVO.
Analysis
Denial of service in Juniper Junos OS and Junos OS Evolved allows an adjacent IS-IS neighbor to trigger a memory leak in the routing protocol daemon by sending specially crafted update packets. Repeated exploitation exhausts available memory and crashes the rpd process, rendering routing unavailable. …
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Remediation
Within 30 days: Identify affected systems and apply vendor patches as part of regular patch cycle. Monitor vendor channels for patch availability.
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