What is CVE-2025-21590?

CVE-2025-21590 is a medium-severity vulnerability in Juniper Junos, classified under CWE-653. CVSS score: 4.4/10. Published 2025-03-12.

How severe is CVE-2025-21590?

Medium severity. CVSS v3 base score is 4.4 out of 10.

Is CVE-2025-21590 known to be exploited?

Yes. CVE-2025-21590 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2025-03-13), indicating it is being actively exploited. 4 public proof-of-concept repositories are indexed.

Vulnerability in Juniper Junos

CVE-2025-21590

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.

EPSS: 0.017 (75.8th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 4.4 (Medium). Vector: CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:H/A:N.

Affected products

Juniper Junos — versions 21.2, 21.4, 22.2
Juniper Networks Junos Os — versions 0, 21.4, 22.2

Weakness classification (CWE)

CWE-653

CISA KEV (Known Exploited Vulnerabilities)

This CVE is on the CISA KEV catalog, added on 2025-03-13. CISA KEV inclusion means CISA has confirmed in-the-wild exploitation; US federal agencies are required to remediate within a published due date.

BOD 22-01 due date: 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.

Public proof-of-concept exploits

References

sirt@juniper.net (vendor-advisory, Vendor Advisory)
sirt@juniper.net (Third Party Advisory, third-party-advisory)
134c704f-9b21-4f2e-91b3-4a467353bcc0 (US Government Resource)

Frequently asked questions

What is CVE-2025-21590?: CVE-2025-21590 is a medium-severity vulnerability in Juniper Junos, classified under CWE-653. CVSS score: 4.4/10. Published 2025-03-12.
How severe is CVE-2025-21590?: Medium severity. CVSS v3 base score is 4.4 out of 10.
Is CVE-2025-21590 known to be exploited?: Yes. CVE-2025-21590 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2025-03-13), indicating it is being actively exploited. 4 public proof-of-concept repositories are indexed.