Zero-day vulnerability in Juniper Junos OS

Permissions, Privileges, and Access Controls
CVE-2025-21590

Vulnerability details

Advisory: SB2025031279 - Privilege escalation in Juniper Junos OS

Vulnerable component: Juniper Junos OS

CVE-ID: CVE-2025-21590

CVSSv3 score: CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H/E:H/RL:O/RC:C

CWE-ID: CWE-264 - Permissions, Privileges, and Access Controls

Description:

The vulnerability allows a local user to escalate privileges on the system.

The vulnerability exists due to improperly imposed security restrictions. A local privileged user can compromise integrity of the device.

Note, the vulnerability is being exploited in the wild.

External links:

https://cloud.google.com/blog/topics/threat-intelligence/china-nexus-espionage-targets-juniper-routers

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

About zero-day vulnerabilities

Zero-day vulnerability is an undisclosed vulnerability in software that hackers can exploit to compromise computer programs, gain unauthorized access to sensitive data, penetrate networks, etc. We consider vulnerability a zero-day when there is no solution provided from software vendor and the vulnerability is being actively exploited by malicious actors.

Zero-day candidate is a potential zero-day vulnerability in software which might have been used in targeted attacks, however there is no evidence to support this suggestion.