Vulnerability report

Exploited in the wild Confirmed confidence In CISA KEV

CVE-2025-21590

Junos OS: An local attacker with shell access can execute arbitrary code

Juniper Networks / Junos OS · affected before 21.2R3-S9

Watch CVE-2025-21590 Browse KEV feed
Severity
CVSS 6.7 · Medium
Confidence
Confirmed
Exploit status
Exploited in the wild
EPSS
1.7%
First observed
—
Last observed
—

Decision summary

What security teams need to know first

Direct answers before the deeper technical record.

What it is

CVE-2025-21590 is Junos OS: An local attacker with shell access can execute arbitrary code. An Improper Isolation or Compartmentalization vulnerability in the kernel of Juniper Networks Junos OS allows a local...

Is it exploited?

Yes. Previdian tracks this CVE as a known exploited vulnerability. Confidence is confirmed. Listed in CISA KEV.

Who is affected?

Juniper Networks / Junos OS affected before 21.2r3-s9.

What should we do?

Prioritize remediation. Validate affected assets and apply vendor fixes on an accelerated timeline.

Overview

Junos OS: An local attacker with shell access can execute arbitrary code

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.

Juniper Networks Affected
Junos OS
Before 21.2R3-S9 Before 21.4R3-S10 Before 22.2R3-S6 Before 22.4R3-S6 Before 23.2R2-S3 Before 23.4R2-S4 Before 24.2R1-S2, 24.2R2
View vendor advisory (opens in new tab)
Published
12 Mar 2025
Exploitation Reported
13 Mar 2025
Attack vector
Local
Complexity
Low
Privileges
High
User interaction
None

Tags

cisa edge nessus_scanner

CVE References

Exploitation evidence

Why Previdian marks this CVE as exploited

Third-party attestation and first-party sensor observation are shown separately so teams can judge the evidence chain.

Exploited in the wild

CISA

Recorded 13 Mar 2025

A trusted third party reported exploitation.

Known exploited vulnerability sources

Per-source evidence links for KEV attestations are available through the Previdian Pro API.

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Source Added
CISA First 2025-03-13 00:00 UTC

Detection

Operational artifacts and observed signals

Make the evidence actionable in scanner, SOC, and edge-control workflows.

Observed signals

Request targets
User-Agents
Callback hosts
0
0
0

Request targets and User-Agents available in Pro. Callback host details available in Enterprise.

Virtual patch status

No Previdian virtual patch is currently available. Future rules ship for ModSecurity, Cloudflare, and AWS WAF.

Learn about virtual patches →

Scanner Artifacts

Scanner and exploit-framework references linked to this CVE.

Scanner Reference Detected
Nessus https://www.tenable.com/plugins/nessus/232834 02 Jun 2025

Risk and context

Severity, weaknesses, and research context

CVSS v4.0

6.7 Medium

Potential damage if exploited. Separate from whether attackers are using it.

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

EPSS

1.7%

Estimated chance of exploitation in the next 30 days. Previdian's warning comes from evidence, not this score.

Weaknesses

Improper Isolation or Compartmentalization CWE-653

All CVSS Scores

CVSS v4.0 6.7 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

CVSS v3.1 4.4 Medium

CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:H/A:N

Timeline

From disclosure to observed exploitation

  1. 09:25 UTC

    Nessus plugin available

    Scanner coverage available

  2. 00:00 UTC

    Added to CISA KEV

    Listed in the CISA Known Exploited Vulnerabilities catalog

  3. 13:59 UTC

    CVE published

    Vulnerability disclosed publicly

  4. 14:47 UTC

    CVE ID reserved

    Identifier reserved by the CNA

Pro API

Automate this intelligence

Confidence, exploit status, sensor telemetry, PoCs, scanner integrations, mentions, and tags are available programmatically for VM, SOC, and CTI workflows.

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  • Evidence confidence and provenance
  • First-party sensor telemetry
  • PoC and scanner references
  • Affected versions and enrichment
  • Automation-ready JSON delivery

GET /api/v2/pro/kevs/CVE-2025-21590

Sample API response 
{
  "cve_id": "CVE-2025-21590",
  "confidence": "Confirmed",
  "cvss_score": 6.7,
  "cvss_estimated": false,
  "epss_score": 0.01735,
  "exploit_status": {
    "exploited_in_the_wild": true,
    "active_exploitation_observed": false
  },
  "sensor_telemetry": { "attempts": 0, "sensors": 0 }
}