FalehSec Exploited-vulnerability triage · joined from CISA KEV, NVD CVSS and EPSS

CVE-2025-21590

Juniper · Junos OS · Juniper Junos OS Improper Isolation or Compartmentalization Vulnerability

Verdict
Patch on your normal cycle · actively exploited, not reachable unauthenticated from the internet, and in the top 25% of CVEs by near-term exploitation probability

Added to CISA KEV 2025-03-13 · exploited in the wild for 563 days

What an attacker can reach How likely Time What CISA says to do Sources All 545

What an attacker can reach

CVSS 6.7 MEDIUM. The score is a summary; these three components are the part that decides whether something scanning the internet can use it.

Attack vectorlocalrequires local access to the machine
Privileges requiredhighneeds elevated privileges before it can be used
User interactionnonecan be triggered with nobody interacting with the page or request
Base vectorCVSS: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
WeaknessCWE-653

This describes the vulnerability. It says nothing about whether your systems run it.

How likely

EPSS puts the probability of exploitation in the next 30 days at 0.0171, which places it in the top 25% of all tracked CVEs. The percentile is the more useful half: 0.18 in absolute terms sounds low until you know most of the internet-facing software in the world scores under that.

EPSS probability0.0171
Percentile0.765 — top 25%

Time

Added to KEV2025-03-13
Days exploited563
Federal remediation duenot set
Ransomware useno known ransomware campaign use

What CISA says to do

Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

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.

Sources