CISA KEV · Known exploitedMedium

CVE-2025-21590

Juniper Junos OS

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...

CVSS
6.7
EPSS
1.66%
74.3% percentile
CISA KEV
Listed
Published
2025.03.12
PRIORITY ASSESSMENT

Immediate review

CISA has listed this vulnerability in the Known Exploited Vulnerabilities catalog.

Known exploitationConfirmed by CISA KEV
Exploit probability1.66%
Technical severityCVSS 6.7

Vulnerability overview

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...

Affected product and versions

Product
Juniper Junos OS
Affected versions
21.4, 22.2, 22.4, 23.2, 23.4, 24.2, <= 21.2, 21.2
Fixed versions
No verified fixed-version field is available yet

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide
CISA required action

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

Due date: 2025.04.03
  1. 1
    Identify

    Confirm that Juniper Junos OS and an affected version are present.

  2. 2
    Prioritize

    Combine exploitation signals with asset exposure and business criticality.

  3. 3
    Remediate

    Follow the vendor advisory or supported update path and preserve rollback options.

  4. 4
    Verify

    Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector
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
CWE
CWE-653
KEV added
2025.03.13
Ransomware use
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