CVE-2025-21590
MediumExploitedPublic exploitAn 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.
Published Mar 12, 2025 · Updated Oct 1, 2026
Key Facts
Patch immediately- CVE-2025-21590 is a medium-severity vulnerability (CVSS 6.7 v4) affecting Junos (Juniper), Junos OS.
- It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since Mar 12, 2025. Public exploit code is available.
- EPSS estimates a 1.7% probability of exploitation in the next 30 days.
- Fixed versions are available, including Junos <=21.2, Junos 21.2, Junos OS 21.2R3-S9.
- Brandefense priority: patch immediately, because it is listed as exploited in the wild.
CVSS v4
6.7
CVSS:4.0/AV:L/AC:L/AT:N/PR:H/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
EPSS (30-day exploit likelihood)
1.7%
Higher than 77.2% of all scored CVEs
Exploited in the wild
Yes
4 catalog listings
Public exploit code
Available
Proof-of-concept or weaponized module
Get the full CVE-2025-21590 brief as a PDF
Every affected product and fixed release, exploitation status and a first 24 hours response checklist, emailed within minutes.
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.
Known-Exploited Catalog Listings
| Catalog | Added | Remediation due | Ransomware use |
|---|---|---|---|
| CISA KEV | Mar 13, 2025 | Apr 3, 2025 | Not reported |
| Industry KEV feed | Mar 12, 2025 | Apr 3, 2025 | Not reported |
| CIRCL KEV | Mar 13, 2025 | Apr 3, 2025 | Not reported |
| ENISA EUVD | Mar 13, 2025 | n/a | Not reported |
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.
Affected Products
85 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| JunosJuniper | 21.2, 21.2-r1, 21.2-r1-s1, 21.2-r1-s2, 21.2-r2, 21.2-r2-s1, 21.2-r2-s2, 21.2-r3 | 21.2 |
| Junos OS | >= 21.4 | 21.2R3-S9 |
Patched Releases
Junos
<=21.2, 21.2
Junos OS
21.2R3-S9, 21.4R3-S10, 22.2R3-S6, 22.4R3-S6, 23.2R2-S3, 23.4R2-S4, 24.2R1-S2, 24.2R2
Timeline
Publicly disclosed
Mar 12, 2025
Added to Industry KEV feed
Mar 12, 2025
Added to CISA KEV
Mar 13, 2025
Added to CIRCL KEV
Mar 13, 2025
Added to ENISA EUVD
Mar 13, 2025
Last updated
Oct 1, 2026
Weakness Type
- CWE-653 Improper Isolation or Compartmentalization
References
- advisoryVulnCheck exploitation report
- advisoryhttps://supportportal.juniper.net/JSA93446
- exploitVulnCheck exploitation report
- exploitVulnCheck exploitation report
- exploitVulnCheck exploitation report
FAQ
Common Questions.
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.
Affected: Junos (Juniper) versions 21.2, 21.2-r1, 21.2-r1-s1, 21.2-r1-s2, 21.2-r2, 21.2-r2-s1, 21.2-r2-s2, 21.2-r3; Junos OS versions >= 21.4. The full list is in the CVE brief.
It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since Mar 12, 2025.
Yes. It was added on Mar 13, 2025 with a federal remediation due date of Apr 3, 2025.
Public exploit code is available.
Fixed versions are available, including Junos <=21.2, Junos 21.2, Junos OS 21.2R3-S9.
Brandefense priority: patch immediately, because it is listed as exploited in the wild.
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