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

CVE-2025-21590 · Severity: critical · CVSS 6.7 · Exploited in the wild · Published 2025-03-13

An improper isolation vulnerability in the Juniper Junos OS kernel allows a local attacker with high privileges and shell access to inject arbitrary code. The vulnerability cannot be exploited via the Junos CLI but can lead to a full compromise of device integrity.

Technologies: Juniper Junos OS. Vendors: Juniper.

Quick answers

Is CVE-2025-21590 exploited in the wild?
Yes. CVE-2025-21590 is known to be exploited in the wild, first recorded on 13 March 2025. Treat it as urgent.
How severe is CVE-2025-21590?
Critical severity, with a CVSS score of 6.7, published 13 March 2025.
Which products and versions are affected?
Juniper Networks 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.
Is there a fix for CVE-2025-21590?
No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2025-21590 attacked?
It is attacked with local access, in an operating system.
Am I affected by CVE-2025-21590?
Check whether you run Juniper Junos OS. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Affected products

  • Juniper Networks 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

Timeline

  • 2025-03-12: disclosed: New CVE received from Juniper Networks
  • 2025-03-13: kev added: Added to CISA Known Exploited Vulnerabilities Catalog
  • 2025-03-13: exploited: Reported as exploited in the wild by CISA and Google Cloud/Mandiant blog

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