Juniper · Junos OS
CVE-2025-21590
Junos OS: An local attacker with shell access can execute arbitrary code
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.
CISA: Juniper Junos OS contains an improper isolation or compartmentalization vulnerability. This vulnerability could allows a local attacker with high privileges to inject arbitrary code.
What to do
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Deadline for US federal agencies: April 3, 2025
More exploited flaws from Juniper
| Added | Vulnerability | Product | Severity | Attack chance |
|---|---|---|---|---|
| Nov 13, 2023 | EX Series PHP External Variable Modification | Junos OS | Medium 5.3 | 90% |
| Nov 13, 2023 | EX Series and SRX Series PHP External Variable Modification | Junos OS | Critical 9.8 | 95% |
| Nov 13, 2023 | SRX Series Missing Authentication for Critical Function | Junos OS | Medium 5.3 | 93% |
| Nov 13, 2023 | EX Series Missing Authentication for Critical Function | Junos OS | Medium 5.3 | 83% |
| Nov 13, 2023 | SRX Series Missing Authentication for Critical Function | Junos OS | Medium 5.3 | 1.1% |
| Mar 25, 2022 | Path Traversal | Junos OS | High 8.8 | 4.9% |
| Oct 2, 2025 | Improper Authentication | ScreenOS | Critical 9.8 | 61% |
Sources: Known Exploited Vulnerabilities (CISA, public domain), CVE records (cve.org) and EPSS (FIRST). The chance of attacks is the EPSS estimate that someone will try to exploit the flaw in the next 30 days.