CVE-2024-39521: Junos OS Evolved: CLI parameter processing issue allows privilege escalation

Severity: high (CVSS 7.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-07-11 · updated 2026-06-17
Weakness: CWE-78

Description

An Improper Neutralization of Special Elements vulnerability in Juniper Networks Junos OS Evolved commands allows a local, authenticated attacker with low privileges to escalate their privileges to 'root' leading to a full compromise of the system. The Junos OS Evolved CLI doesn't properly handle command options in some cases, allowing users which execute specific CLI commands with a crafted set of parameters to escalate their privileges to root on shell level. This issue affects Junos OS Evolved: * 21.1-EVO versions 21.1R1-EVO and later before 21.2R3-S8-EVO, * 21.4-EVO versions before 21.4R3-S7-EVO, * 22.1-EVO versions before 22.1R3-S6-EVO, * 22.2-EVO versions before 22.2R3-EVO, * 22.3-EVO versions before 22.3R2-EVO.

Affected products

Juniper Networks Junos OS Evolved: from 21.1 before 21.2; 21.2, 21.2-r1, 21.2-r1-s1, 21.2-r1-s2, 21.2-r2, 21.2-r2-s1 (+33) — fixed in 21.2

How to fix

Upgrade to a fixed version: Juniper Networks Junos OS Evolved 21.2. Check the vendor advisory for mitigations.

References

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