CVE-2025-21590

CVE-2025-21590 is a medium-severity vulnerability in Juniper Junos with a CVSS 3.x base score of 4.4. It is listed in CISA's Known Exploited Vulnerabilities (KEV) catalog, confirming it has been exploited in the wild (added 2025-03-13). The underlying weakness is classified as CWE-653.

Key facts

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.

Frequently asked questions

What is 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.
How severe is CVE-2025-21590?
CVE-2025-21590 has a CVSS 3.x base score of 4.4, rated medium severity. It is exploitable over local access with low attack complexity, requires high privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability none.
Is CVE-2025-21590 being actively exploited?
Yes. CVE-2025-21590 is on CISA's Known Exploited Vulnerabilities (KEV) catalog, added on 2025-03-13, which means active exploitation has been confirmed. It should be prioritised for remediation.
What products are affected by CVE-2025-21590?
CVE-2025-21590 primarily affects Juniper Junos. In total, 82 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2025-21590?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Because this CVE is known to be actively exploited, treat remediation as urgent — CISA KEV typically sets a short remediation deadline.
Does CVE-2025-21590 have an EU (EUVD) identifier?
Yes. CVE-2025-21590 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-6303. It is also flagged as exploited in the EUVD (since 2025-03-13).
When was CVE-2025-21590 published?
CVE-2025-21590 was published on 2025-03-12 and last updated on 2026-06-17.

References

Affected products (82)

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