Junos OS <21.2R3-S9: Improper Isolation Allows Local Privileged Code Injection
CVE-2025-21590 Published on March 12, 2025
Junos OS: An local attacker with shell access can execute arbitrary code
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.
Known Exploited Vulnerability
This Juniper Junos OS Improper Isolation or Compartmentalization Vulnerability is part of CISA's list of Known Exploited Vulnerabilities. Juniper Junos OS contains an improper isolation or compartmentalization vulnerability. This vulnerability could allows a local attacker with high privileges to inject arbitrary code.
The following remediation steps are recommended / required by April 3, 2025: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Vulnerability Analysis
CVE-2025-21590 is exploitable with local system access, and requires user privileges. This vulnerability is considered to have a low attack complexity. This vulnerability is known to be actively exploited by threat actors. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality, a high impact on integrity, and no impact on availability.
Timeline
Initial Publication
Corrected hotlinks for CVSS assessments
Rephrased sentences on Amazon involvement to reduce the chance for confusion 2 days later.
Updated solution section to clarify which platforms are not fixed in all but only in specific releases 26 days later.
For the products/platforms specifically mentioned in the solution section: Please note that Junos OS version 21.2R3-S9.20, which was made available last week, does not address the issue completely. We'll publish an updated version with the complete fix and update this advisory as soon as possible. 5 days later.
For the products/platforms specifically mentioned in the solution section: Please note that Junos OS version 21.2R3-S9.21 has been publish with the complete fix. 22 days later.
Weakness Type
What is a Separation of Privilege Vulnerability?
The product does not sufficiently compartmentalize functionality or processes that require different privilege levels, rights, or permissions. When a weakness occurs in functionality that is accessible by lower-privileged users, then without strong boundaries, an attack might extend the scope of the damage to higher-privileged users.
CVE-2025-21590 has been classified to as a Separation of Privilege vulnerability or weakness.
Products Associated with CVE-2025-21590
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Affected Versions
Juniper Networks Junos OS:- Before 21.2R3-S9 is affected.
- Version 21.4 and below 21.4R3-S10 is affected.
- Version 22.2 and below 22.2R3-S6 is affected.
- Version 22.4 and below 22.4R3-S6 is affected.
- Version 23.2 and below 23.2R2-S3 is affected.
- Version 23.4 and below 23.4R2-S4 is affected.
- Version 24.2 and below 24.2R1-S2, 24.2R2 is affected.
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.