CVE-2025-21590 on CISA KEV

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.

01What CISA says about this vulnerability

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.

02Required action — verbatim from CISA

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

03Notes & references

• supportportal.juniper.net — https://supportportal.juniper.net/JSA93446
• cloud.google.com — https://cloud.google.com/blog/topics/threat-intelligence/china-nexus-espionage-t…

04SARA's analyst layer — why this matters

This vulnerability is currently on the CISA KEV list, which CISA only adds CVEs to when there is reliable evidence of active exploitation in the wild. For federal civilian agencies, BOD 22-01 requires remediation by the due date above. For everyone else, KEV is the strongest "patch immediately" signal you can get from public threat intel.

05Affected products (summary)

Vendor	Product	Versions
Juniper Networks	Junos OS	0, 21.4, 22.2, 22.4, 23.2, 23.4, 24.2

06Detection

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