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CVE-2025-21590

56
FAUCET Score

CVE-2025-21590 is an improper isolation vulnerability in Juniper Networks Junos OS kernel, affecting numerous versions across multiple release trains. A local attacker with high privileges and shell access can inject arbitrary code, compromising device integrity. This vulnerability has a CVSS score of 4.4 (Medium) due to its local attack vector and high privileges required, but it can lead to high integrity impact. Notably, this CVE is actively exploited in the wild, as indicated by its presence in the KEV catalog, and has garnered significant community discussion and media coverage despite a lack of public exploit code.

Impacted Technologies

VendorProductVersion(s)CPE
<= 21.2CPE matchmatch criteria
cpe:2.3:o:juniper:junos:*:-:*:*:*:*:*:*
21.2CPE matchmatch criteria
cpe:2.3:o:juniper:junos:21.2:r1:*:*:*:*:*:*
21.2CPE matchmatch criteria
cpe:2.3:o:juniper:junos:21.2:r1-s1:*:*:*:*:*:*
21.2CPE matchmatch criteria
cpe:2.3:o:juniper:junos:21.2:r1-s2:*:*:*:*:*:*
21.2CPE matchmatch criteria
cpe:2.3:o:juniper:junos:21.2:r2:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 4.0

6.7MEDIUM

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

Attack Vector
LOCAL
Attack Complexity
LOW
Attack Requirements
NONE
Privileges Required
HIGH
User Interaction
NONE
VS Confidentiality
NONE
VS Integrity
HIGH
VS Availability
NONE
SS Confidentiality
NONE
SS Integrity
NONE
SS Availability
NONE
Exploit Maturity
NOT_DEFINED
CvssVersion
4.0

Exploit Intelligence

EPSS Score
1.66%
Probability of exploitation in next 30 days
EPSS Percentile
74.2%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
Added to KEV · Mar 13, 2025
This CVE's current EPSS score of 0.0166 is in the 99th percentile among its peer group of 3,720 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.0 Bluesky, 0.0 Mastodon, and 0.1 GitHub mentions.

Media Mentions

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Remediation records are not available for this CVE.

References

cisa.gov / known-exploited-vulnerabilities-catalog
US Government Resource
cloud.google.com / blog/topics/threat-intelligence/china-nexus-espionage-targets-juniper-routers
Third Party Advisory
supportportal.juniper.net / JSA93446
Vendor Advisory