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Juniper Junos OS: Junos OS Improper Isolation or Compartmentalization Vulnerability

Juniper Junos OS

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 CISA KEV on 2025-03-13.

Why this severity: CVSS 4.4 (CNA, v3.1); actively exploited (CISA KEV)

Started: Mar 13, 2025
Closed: Mar 13, 2025
CVE: CVE-2025-21590

Follow this incident

Updated Mar 13, 2025

Affected

See vendor advisory / CISA notes (versions not always listed in KEV feed)

Fixed in

See vendor advisory linked in sources

Timeline1

Mar 13, 2025
CISA added CVE-2025-21590 to the KEV catalog (due 2025-04-03).

Advisories3

Notes & caveats

Derived from CISA KEV JSON feed catalogVersion 2026.10.21. CVSS from the CVE record (cvelistV5). Exact affected/fixed version strings are not always in the KEV record; verify against the vendor advisory URL. startedAt uses dateAdded (exploitation may have begun earlier; many entries are older CVEs newly confirmed as exploited in 2025).

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