medium Known exploitedREV. 01

CVE-2025-21590Juniper Junos OS — shell access injects code into the kernel

The kernel in Juniper's router software (Junos OS) does not isolate components properly, so a local attacker with shell access and high privileges injects code and compromises the device's integrity.

YOUR NEXT MOVE

Apply the Juniper fix from JSA93446 now; a China-linked group targets these routers, so restrict shell access and check for unexpected kernel modules.

Read the risk

THE VITAL STATS
CVSS score
6.7/ 10
CVSS v4.0
EPSS probability
2%
Likelihood of exploitation
Attack complexity
Low
Conditions needed to exploit
Known exploited
Yes — CISA KEV
CVE published
2025-03-12
Added to KEV
2025-03-13
Exploit published
Not recorded
Confidence
high
Kill chain
privilege escalation
MITRE ATT&CK
—
Severity
medium

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

Attacker needsLocal shell access on the device with high privileges.

Behind the card

4 REFERENCES
Field-level provenanceTRACE THE SOURCES +

Which source supports each field, when it was retrieved, and who extracted it.

FieldsSourceRetrievedExtractorConfidence
cvss, exploitation.attack_complexity, exploitation.exploit_available, references, published_atnvd.nist.gov2026-09-24scrty-crds-pipeline/0.1high
exploitation.known_exploited, exploitation.kev_addedcisa.gov2026-09-24scrty-crds-pipeline/0.1high
epssapi.first.org2026-09-24scrty-crds-pipeline/0.1high
title, summary, severity, remediation, mitre_attack, kill_chain, recommended_action, confidence, tags, exploitation.prerequisitesnvd.nist.gov2026-09-24claude-codehigh

Printing history

THE RECORD
  1. r1Initial base card

First printing. This card has not been reprinted since publication.

crds:cve-2025-21590 · CRDS 0.1 · Issued 2026-09-24