Threats / Juniper / CVE-2025-21590
CVE-2025-21590
· EUVD no mirror located
· GCVE no mirror located
Verified 2026-06-22
Juniper Junos OS vulnerability
Juniper Junos OS contains an improper isolation vulnerability allowing local attackers with high privileges to inject arbitrary code, potentially compromising system integrity.
Verdict
Today item — known-exploited.
A local privilege escalation and code injection flaw in Junos OS enables authenticated high-privilege users to bypass compartmentalization controls and execute arbitrary code, risking unauthorized system modification and lateral movement.
01
Is it exploitable?
— the evidence, ranked above the scoreReported exploitation
9 independent public reports of in-the-wild exploitation are cataloged.Distinct reporting sources (vendor, incident response, government); open them for the underlying claims.
Exploited in the wild
Listed in the CISA Known Exploited Vulnerabilities catalog (added 2025-03-13).
Probability (EPSS)
EPSS 0.01657 — modeled likelihood of exploitation activity.EPSS is a daily-changing model output — open the source for today's value.
Severity / affected
Affected: Juniper, Junos OS. Confirm exact fixed builds in the vendor advisory.
Weakness (CWE)
Mapped to CWE-653 CWE-653.CWE assignment from the public NVD record; the weakness class drives how the flaw is exploited.
WeaknessCWE-653 · CWE-653
02
Who’s exploiting it?
— attribution turns risk into urgencyAttribution not established
No confirmed (advisory-backed) threat-actor attribution is established for this record. Absence of a named actor is not absence of compromise — see Coverage & confidence.
03
Why it matters
— the attack path, told twice: adversary, then board1
Front door — unauthenticated access narrative 1
Attacker
I establish local access to the Junos OS system with high-level privileges.
Business
An insider or compromised administrator account gains foothold on critical network infrastructure.
2
Keys to the kingdom — privilege/identity takeover narrative 2
Attacker
I exploit the improper isolation flaw to inject arbitrary code across security boundaries.
Business
System compartmentalization fails, allowing code execution in protected contexts and undermining defense-in-depth architecture.
3
Lateral reach — past segmentation narrative 3
Attacker
I execute malicious code with elevated privileges to modify system behavior or persistence mechanisms.
Business
Junos OS integrity is compromised, enabling unauthorized configuration changes, data exfiltration, or sustained control of network devices.
04
What to do
— defensible action- Remediate per the vendor advisory — confirm the fixed build for your version and verify exposure.1
Say it to the boardA vulnerability with this evidence profile is a defensible budget line, not a backlog ticket — fund the change against the proof above.
05