How severe is CVE-2025-21590?

CVE-2025-21590 has a CVSS 4.0 base score of 6.7 (MEDIUM). EPSS estimates a 1.7% probability of exploitation in the next 30 days. It is listed in the CISA Known Exploited Vulnerabilities catalog.

CVE-2025-21590: Junos OS: An local attacker with shell access can

CISA Known Exploited Vulnerabilities

Juniper Junos OS Improper Isolation or Compartmentalization Vulnerability is confirmed as actively exploited and is listed in the CISA KEV catalog.

Added to KEV

2025-03-13

Remediation due

2025-04-03

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.

CISA 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

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.

Severity

CVSS 3.1 · CNA4.4 MEDIUM

CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:H/A:N

CVSS 4.0 · CNA6.7 MEDIUM

CVSS:4.0/AV:L/AC:L/AT:N/PR:H/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N

SSVC · CISA-ADP

Exploitationactive

Automatableno

Technical impacttotal

Affected Products

Vendor	Product	Affected versions
Juniper Networks	Junos OS	0 to <21.2R3-S9 21.4 to <21.4R3-S10 22.2 to <22.2R3-S6 22.4 to <22.4R3-S6 23.2 to <23.2R2-S3 23.4 to <23.4R2-S4 24.2 to <24.2R1-S2, 24.2R2

References

2 Links

Vendor advisories

https://supportportal.juniper.net/JSA93446

Third-party advisories

https://cloud.google.com/blog/topics/threat-intelligence/china-nexus-espionage-targets-juniper-routers

Record Details

Published

2025-03-12

Last updated

2026-02-26

Assigner (CNA)

juniper

Credited to

Juniper SIRT would like to acknowledge and thank Matteo Memelli from Amazon for responsibly reporting this issue. Note: Amazon found the issue during internal security research and not due to exploitation.

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Related Tool Categories

Tool categories that test for or protect against this vulnerability class.

CWE-653 · Improper Isolation or Compartmentalization

Application Security Tools

CVE record data © The MITRE Corporation, used under the CVE Terms of Use. Exploited-in-the-wild data from the CISA Known Exploited Vulnerabilities catalog (CC0). Exploit prediction scores by FIRST EPSS (first.org/epss). This site is not endorsed or certified by MITRE, NVD, CISA, or FIRST.