PT-2026-3132 · Juniper Networks · Chassisd+4

Published 2026-01-15 · Updated 2026-01-15 · CVE-2026-21921

Positive Technologies (AI Summary)

CVSS v3.1

6.5

Medium

Base vector

AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Name of the Vulnerable Software and Affected Versions Juniper Networks Junos OS versions prior to 22.4R3-S8 Juniper Networks Junos OS versions 23.2 before 23.2R2-S5 Juniper Networks Junos OS versions 23.4 before 23.4R2 Juniper Networks Junos OS Evolved versions prior to 22.4R3-S8-EVO Juniper Networks Junos OS Evolved versions 23.2 before 23.2R2-S5-EVO Juniper Networks Junos OS Evolved versions 23.4 before 23.4R2-EVO

Description A Use After Free issue exists in the chassis daemon (chassisd) of Juniper Networks Junos OS and Junos OS Evolved. A network-based attacker with low privileges can trigger a Denial-of-Service (DoS). The issue occurs when telemetry collectors frequently subscribe and unsubscribe to sensors over an extended period. This leads to telemetry-capable processes, including chassisd, rpd, and mib2d, crashing and restarting, potentially causing a complete outage until system recovery.

Recommendations Upgrade Junos OS to version 22.4R3-S8 or later. Upgrade Junos OS to version 23.2R2-S5 or later. Upgrade Junos OS to version 23.4R2 or later. Upgrade Junos OS Evolved to version 22.4R3-S8-EVO or later. Upgrade Junos OS Evolved to version 23.2R2-S5-EVO or later. Upgrade Junos OS Evolved to version 23.4R2-EVO or later.

Fix

DoS

Use After Free

Weakness Enumeration

CWE-416

Related Identifiers

CVE-2026-21921

Affected Products

Junos

Junos Evolved

Chassisd

Mib2D

Rpd

References · 6

• https://kb.juniper.net/JSA106021 · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2026-21921 · Security Note
• https://supportportal.juniper.net/JSA106021 · Vendor Advisory
• https://osv.dev/vulnerability/CVE-2026-21921 · Vendor Advisory
• https://twitter.com/VulmonFeeds/status/2011923060421538035 · Twitter Post
• https://twitter.com/CVEnew/status/2011926034170761508 · Twitter Post