CVEs / CVE-2025-21590
CVE-2025-21590: Juniper Junos OS Improper Isolation or Compartmentalization Vulnerability
- Known exploited in the CISA KEV catalog since 13 Mar 2025
- medium 6.7 CVSS 4.0 (from the CNA)
- EPSS 1.73% chance of exploitation in the next 30 days, higher than 77% of CVEs (30 Oct 2026)
- Last changed at its sources
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Summary
Juniper Junos OS contains an improper isolation or compartmentalization vulnerability. This vulnerability could allows a local attacker with high privileges to inject arbitrary code.
Description
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.
Affected and fixed versions
| Product | Affected | Fixed in |
|---|---|---|
| Juniper Networks Junos OS | before 21.2R3-S9 | 21.2R3-S9 |
| Juniper Networks Junos OS | from 21.4, before 21.4R3-S10 | 21.4R3-S10 |
| Juniper Networks Junos OS | from 22.2, before 22.2R3-S6 | 22.2R3-S6 |
| Juniper Networks Junos OS | from 22.4, before 22.4R3-S6 | 22.4R3-S6 |
| Juniper Networks Junos OS | from 23.2, before 23.2R2-S3 | 23.2R2-S3 |
| Juniper Networks Junos OS | from 23.4, before 23.4R2-S4 | 23.4R2-S4 |
| Juniper Networks Junos OS | from 24.2, before 24.2R1-S2, 24.2R2 | 24.2R1-S2, 24.2R2 |
Exploitation
| In CISA KEV since | 13 Mar 2025 |
|---|---|
| Due date for US federal agencies | 3 Apr 2025 |
| Used in ransomware campaigns | Unknown |
| 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. |
Severity
| CVSS 4.0 | 6.7 mediumCVSS: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:XScored by the CNA ([email protected]) |
|---|---|
| Weakness | CWE-653 |
References
- CVE-2025-21590 on NVD
- CVE-2025-21590 in the CISA KEV catalog
- https://supportportal.juniper.net/s/article/2025-03-Out-of-Cycle-Security-Bulletin-Junos-OS-A-local-attacker-with-shell-access-can-execute-arbitrary-code-CVE-2025-21590?language=en_US (cited by CISA)
- https://cloud.google.com/blog/topics/threat-intelligence/china-nexus-espionage-targets-juniper-routers Third Party Advisory
- https://supportportal.juniper.net/JSA93446 Vendor Advisory
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-21590 US Government Resource
Sources
Exploitation status from the CISA Known Exploited Vulnerabilities catalog. EPSS scores from FIRST. Descriptions, severity and references from the National Vulnerability Database. Open-source package versions from OSV (CC-BY 4.0). Text is shown as each source states it; Stackurity does not edit it. Check the vendor's advisory before acting.
This product uses data from the NVD API but is not endorsed or certified by the NVD.