Juniper Junos OS Improper Isolation or Compartmentalization Vulnerability
Juniper Junos OS contains an improper isolation or compartmentalization vulnerability. This vulnerability could allows a local attacker with high privileges to inject arbitrary code.
- Vendor
- Juniper
- Product
- Junos OS
- CVSS
- 4.4
- EPSS (exploit probability)
- 1.7%
- Status
- kev
- CISA patch-by (BOD 22-01)
- Added to KEV
Is CVE-2025-21590 being exploited?
Yes. CISA added CVE-2025-21590 to its Known Exploited Vulnerabilities catalog on . CISA only lists a CVE when it has reliable evidence of exploitation in the wild.
FIRST's EPSS model puts the probability of exploitation activity in the next 30 days at 1.7% (scored October 14, 2026).
- CISA KEV[ LISTED ]
- ENISA EUVD (exploited)[ — ]
- CIRCL KEV[ — ]
Catalog snapshot 2026-10-21. Full cross-catalog view: /kev-comparison
What to do
CISA required actionApply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
US federal civilian agencies must remediate by (21 days after listing) under BOD 22-01. Everyone else: that deadline is a sensible upper bound, not a target. Vendor guidance and the NVD record are linked under Source above.
Other Juniper Junos OS CVEs we track
| CVE / Vulnerability | Severity | CVSS | EPSS | Added to KEV |
|---|---|---|---|---|
| CVE-2023-36851 Juniper Junos OS SRX Series Missing Authentication for Critical Function Vulnerability | [ MEDIUM ] | 5.3 | 1.1% | |
| CVE-2023-36847 Juniper Junos OS EX Series Missing Authentication for Critical Function Vulnerability | [ MEDIUM ] | 5.3 | 83.5% | |
| CVE-2023-36846 Juniper Junos OS SRX Series Missing Authentication for Critical Function Vulnerability | [ MEDIUM ] | 5.3 | 93.5% | |
| CVE-2023-36845 Juniper Junos OS EX Series and SRX Series PHP External Variable Modification Vulnerability | [ CRITICAL ] | 9.8 | 95.1% | |
| CVE-2023-36844 Juniper Junos OS EX Series PHP External Variable Modification Vulnerability | [ MEDIUM ] | 5.3 | 90.0% | |
| CVE-2020-1631 Juniper Junos OS Path Traversal Vulnerability | [ HIGH ] | 8.8 | 4.9% |