CVE WatchOct 1, 2026

CVE-2025-21590

Juniper Junos OS Improper Isolation or Compartmentalization Vulnerability

CVSS

4.4

Medium

EPSS

1.7%

p77

KEV

YES

Mar 13, 2025

Exploit Today

0-100

Published: Mar 12, 2025 · Last modified: Oct 1, 2026 · CWE-653

EPSS · 30d

1.7%EPSS · 30 days1.7%

2026-09-162026-10-14

KEV catalog record

Product

Juniper / Junos OS

Vulnerability

Juniper Junos OS Improper Isolation or Compartmentalization Vulnerability

Added to KEV

Mar 13, 2025

Remediate by

Apr 3, 2025

Known ransomware use

Summary description

Juniper Junos OS contains an improper isolation or compartmentalization vulnerability. This vulnerability could allows a local attacker with high privileges to inject arbitrary code.

Required action

Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

Notes

https://supportportal.juniper.net/s/article/2025-03-Out-of-Cycle-Security-Bulletin-Junos-OS-A-local-attacker-with-shell-access-can-execute-arbitrary-code-CVE-2025-21590?language=en_US ; https://nvd.nist.gov/vuln/detail/CVE-2025-21590

Technical 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.

Official references

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