CVE-2025-21590: An local attacker with shell access can execute arbitrary code

Automatic summary from the vendor's CVE record. We haven't written a full analysis of this vulnerability yet.

Affected and fixed versions

Product / branch	Fixed in
Junos OS 0	21.2R3-S9 or later
Junos OS 21.4	21.4R3-S10 or later
Junos OS 22.2	22.2R3-S6 or later
Junos OS 22.4	22.4R3-S6 or later
Junos OS 23.2	23.2R2-S3 or later
Junos OS 23.4	23.4R2-S4 or later
Junos OS 24.2	24.2R1-S2, 24.2R2 or later

Always confirm against the vendor advisory, which lists every fixed hotfix.

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.

Workarounds

It is strongly recommended to mitigate the risk of exploitation by restricting shell access to trusted users only.

Exploitation

At least one instance of malicious exploitation has been reported to the Juniper SIRT. Customers are encouraged to upgrade to a fixed release as soon as it's available and in the meantime take steps to mitigate this vulnerability.

CISA lists this CVE as exploited in the wild since 13 Mar 2025.

KEV status, EPSS score and vendor data refreshed automatically, last on 13 Oct 2026.