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Medium severity6.5NVD Advisory· Published Jan 15, 2026· Updated Jun 17, 2026

CVE-2026-21909

CVE-2026-21909

Description

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.

Affected products

23
  • Juniper Networks/Junos11 versions
    cpe:2.3:o:juniper:junos:23.2:-:*:*:*:*:*:*+ 10 more
    • cpe:2.3:o:juniper:junos:23.2:-:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:23.2:r1-s1:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:23.2:r1-s2:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:23.2:r1:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:23.4:-:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:23.4:r1-s1:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:23.4:r1:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:23.4:r2:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:24.1:-:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:24.1:r1:*:*:*:*:*:*
    • (no CPE)range: from 23.2 before 23.2R2, from 23.4 before 23.4R1-S2, 23.4R2, from 24.1 before 24.1R2
  • Juniper Networks/OS Evolved12 versions
    cpe:2.3:o:juniper:junos_os_evolved:23.2:-:*:*:*:*:*:*+ 11 more
    • cpe:2.3:o:juniper:junos_os_evolved:23.2:-:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos_os_evolved:23.2:r1-s1:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos_os_evolved:23.2:r1-s2:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos_os_evolved:23.2:r1:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos_os_evolved:23.4:-:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos_os_evolved:23.4:r1-s1:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos_os_evolved:23.4:r1:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos_os_evolved:23.4:r2:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos_os_evolved:24.1:-:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos_os_evolved:24.1:r1:*:*:*:*:*:*
    • (no CPE)range: 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
    • (no CPE)range: 23.2

Patches

Vulnerability mechanics

References

2

News mentions

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