CVE-2026-21921CWE-416

Junos OS and Junos OS Evolved: When telemetry collectors are frequently subscribing and unsubscribing to sensors chassisd or rpd will crash

High · published January 15, 2026

CVSS v4.0
7.1
EPSS
0%
Percentile
29.9
In the wild
Unconfirmed
What it is

A Use After Free vulnerability in the chassis daemon (chassisd) of Juniper Networks Junos OS and Junos OS Evolved allows a network-based attacker authenticated with low privileges to cause a Denial-of-Service (DoS).

When telemetry collectors are frequently subscribing and unsubscribing to sensors continuously over a long period of time, telemetry-capable processes like chassisd, rpd or mib2d will crash and restart, which - depending on the process - can cause a complete outage until the system has recovered.

This issue affects:

Junos OS:

* all versions before 22.4R3-S8,

* 23.2 versions before 23.2R2-S5,

* 23.4 versions before 23.4R2;

Junos OS Evolved:

* all versions before 22.4R3-S8-EVO,

* 23.2 versions before 23.2R2-S5-EVO,

* 23.4 versions before 23.4R2-EVO.

The record
Technical detail
CVSS v4.0
7.1 · HIGH
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/AU:Y/R:A/RE:M
EPSS
0.00372 · 29.9th percentile
Weakness
CWE-416 · Use After Free
Published
2026-01-15T20:28Z
EPSS history
Timeline
  • 15 JAN 20:28Z
    Junos OS and Junos OS Evolved: When telemetry collectors are frequently subscribing and unsubscribing to sensors chassisd or rpd will crash
    cvelistv5