CVE-2025-21590 Juniper Junos OS Improper Isolation or Compartmentalization

Exploited in the wild Medium 6.7 Published 12 Mar 2025 Updated 26 Feb 2026

A local attacker with shell access can inject arbitrary code into the Junos OS kernel, compromising device integrity and executing code.

Exploited in the wild: Since 13 Mar 2025
Login needed: An administrator
Attackable: Local or same network only
Victim action needed: Not needed
Fix: None listed

What is CVE-2025-21590?

CVE-2025-21590 is a medium-severity code injection vulnerability in Juniper Junos, published on 12 Mar 2025. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

An Improper Isolation or Compartmentalization vulnerability in the kernel of Juniper Networks Junos OS allows a local attacker with high privileges to compromise the integrity of the device.

A local attacker with access to the shell is able to inject arbitrary code which can compromise an affected device. This issue is not exploitable from the Junos CLI. This issue affects Junos OS:

* All versions before 21.2R3-S9, * 21.4 versions before 21.4R3-S10, * 22.2 versions before 22.2R3-S6, * 22.4 versions before 22.4R3-S6, * 23.2 versions before 23.2R2-S3, * 23.4 versions before 23.4R2-S4, * 24.2 versions before 24.2R1-S2, 24.2R2.

Weakness: CWE-653

Which versions are affected by CVE-2025-21590?

It affects 1 product.

Products include Juniper Junos.

How do I fix CVE-2025-21590?

No fix has been published for CVE-2025-21590 yet. Limit exposure of the affected software until one is available. US federal agencies must fix it by 3 Apr 2025.

Upgrade, and never evaluate templates, expressions or code built from user input. More about Code injection.

Is CVE-2025-21590 being exploited?

Yes. Attackers have exploited CVE-2025-21590 in the wild since at least 13 Mar 2025.

All Juniper Junos vulnerabilities

Sources

Also known as GHSA-jwv5-xmf5-mp56.