CVE-2025-21590: Juniper Junos OS Improper Isolation or Compartmentalization Vulnerability
Advisory generated from the CVE record, CISA, Exploit Observer and VEDAS: what it is, whether it is exploited, who is affected, and how to fix and detect it.
Generated by VEDAS. Scores as of 2026-11-01 19:19 UTC. Rebuilt every few hours from cve-scores, CISA KEV and vedas-signatures. How this works and its limits.
What it is
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.
Description quoted from the CVE record (assigned by juniper, published 2025-03-12).
Weakness: CWE-653 Improper Isolation or Compartmentalization
How it can be exploited
Exploitable with local access with low attack complexity with no special attack requirements needing high privileges and no user interaction. Impact: confidentiality none, integrity high, availability none. 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
CISA assessment (SSVC): CISA assesses exploitation as active. Automatable: no. Technical impact: total.
- On CISA KEV since
- 2025-03-13
- US federal deadline
- 2025-04-03
- Ransomware use
- Not known
Public exploit evidence (Exploit Observer)
Also known as: BDU:2025-02715, CNNVD-202503-1495, EUVD-2025-6303, GHSA-jwv5-xmf5-mp56
Exploit Observer has no public exploit code that names this CVE or one of its aliases.
Research and write-ups (1)
- Research or write-up: 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
Vulnerability databases and vendor advisories (6)
Catalogue entries, not exploit evidence.
- Vulnerability database or vendor advisory: https://access.redhat.com/security/cve/cve-2025-21590
- Vulnerability database or vendor advisory: https://euvd.enisa.europa.eu/enisa/EUVD-2025-6303
- Vulnerability database or vendor advisory: https://github.com/advisories/GHSA-jwv5-xmf5-mp56
- Vulnerability database or vendor advisory: https://nvd.nist.gov/vuln/detail/CVE-2025-21590
- Vulnerability database or vendor advisory: https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-21590
- Vulnerability database or vendor advisory: https://www.cnnvd.org.cn/home/globalSearch?keyword=CNNVD-202503-1495
60 more references returned by Exploit Observer did not name this CVE or an alias, so they are left out.
VEDAS data as of 2026-11-01T17:12 UTC; fetched 2026-11-02.
Live scores
- EPSS
- 0.017
some chance of attack soon - VEDAS
- 0.511
some exploit evidence - On CISA KEV
- Yes, since 2025-03-13
- Detection rule
- Out of scope (local)
Thin horizontal line: the “likely” (EPSS 0.10) or “strong” (VEDAS 0.90) threshold. Shaded “no data” areas are periods when cve-scores did not publish.
Who is affected
| Product | Affected | Not affected |
|---|---|---|
| Juniper Networks Junos OS | before 21.2R3-S9 from 21.4 before 21.4R3-S10 from 22.2 before 22.2R3-S6 from 22.4 before 22.4R3-S6 from 23.2 before 23.2R2-S3 from 23.4 before 23.4R2-S4 from 24.2 before 24.2R1-S2, 24.2R2 | Not stated |
Version ranges exactly as the CVE record states them. “Before X” means X is the first fixed version.
Exploit Observer also maps it to: juniper junos, juniper_networks_inc. junos.
How to fix it
Fixed versions stated in the CVE record: 21.2R3-S9, 21.4R3-S10, 22.2R3-S6, 22.4R3-S6, 23.2R2-S3, 23.4R2-S4, 24.2R1-S2, 24.2R2.
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.
Vendor guidance:
- https://supportportal.juniper.net/JSA93446 (vendor-advisory)
How to detect it
This bug needs local access to exploit. VEDAS signatures cover remotely exploitable bugs for now, so there is no network rule or remote check for it. Patch it and watch your endpoint telemetry for unusual local activity.
References
Vendor advisories and patches
- https://supportportal.juniper.net/JSA93446 (vendor-advisory)
Exploits and technical analysis
- https://cloud.google.com/blog/topics/threat-intelligence/china-nexus-espionage-targets-juniper-routers (third-party-advisory)
Government sources
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-21590 (government-resource)
Other databases
Where this comes from
This advisory is generated automatically by VEDAS from: CVE.org record, CISA KEV, cve-scores (EPSS and VEDAS), Exploit Observer. Text in quotes is reproduced from the source; everything else is a fixed template filled with source fields. Nothing here is written by a language model. Check the vendor advisory before acting, and read how VEDAS and Exploit Observer work, and their limits.