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CVE-2025-21590

Juniper Junos OS Improper Isolation or Compartmentalization

4.4 MEDIUMActively exploited (CISA KEV)EPSS 1.74%
  1. Published12 Mar 2025
  2. Added to CISA KEV13 Mar 2025
  3. Remediation due3 Apr 2025
Actively exploited (CISA KEV)

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

Added to KEV: 13 Mar 2025Federal remediation due: 3 Apr 2025

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.

CVSS 3.1 breakdown

Attack vectorLocal
Attack complexityLow
Privileges requiredHigh
User interactionNone
ScopeUnchanged
ConfidentialityNone
IntegrityHigh
AvailabilityNone
CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:H/A:N

Affected products

Juniper Junos< 21.2 · 21.2 · 21.4 · 22.2

Remediation

Fixed in
Juniper Junos≥ 21.2

References

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Frequently asked

Is CVE-2025-21590 being actively exploited?

Yes. CVE-2025-21590 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, added 13 Mar 2025.

How severe is CVE-2025-21590?

CVE-2025-21590 has a CVSS 3.1 base score of 4.4, rated medium. EPSS estimates a 1.74% probability of exploitation.

Which products are affected by CVE-2025-21590?

Affected products include Juniper Junos.

How do I fix CVE-2025-21590?

Upgrade affected software to a fixed version, for example Juniper Junos 21.2 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2025-21590 against the real software inventory on every managed device, every day. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. Because it is on the CISA KEV list, Secuno flags any affected asset as top-priority automatically. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

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Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.