CVE-2026-21909CWE-401

Junos OS and Junos OS Evolved: Receipt of specific IS-IS update packet causes memory leak leading to RPD crash

High · published January 15, 2026

CVSS v4.0
7.1
EPSS
0%
Percentile
15.3
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v4.0
7.1 · HIGH
Vector
CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L/AU:Y/R:A/V:C/RE:M/U:Green
EPSS
0.00249 · 15.3th percentile
Weakness
CWE-401 · Missing Release of Memory after Effective Lifetime
Published
2026-01-15T20:22Z
EPSS history
Timeline
  • 15 JAN 20:22Z
    Junos OS and Junos OS Evolved: Receipt of specific IS-IS update packet causes memory leak leading to RPD crash
    cvelistv5