Junos OS Evolved: Multiple shell-injection vulnerabilities in EVO UI wrapper scripts

published 2021-10-19 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-18266

cvss: 7.8; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.9%; EPSS 0.9% chance of exploitation in 30 days, percentile 59%
public exploits: 0; none known

A command injection vulnerability in command processing on Juniper Networks Junos OS Evolved allows an attacker with authenticated CLI access to be able to bypass configured access protections to execute arbitrary shell commands within the context of the current user. The vulnerability allows an attacker to bypass command authorization restrictions assigned to their specific user account and execute commands that are available to the privilege level for which the user is assigned. For example, a user that is in the super-user login class, but restricted to executing specific CLI commands could exploit the vulnerability to execute any other command available to an unrestricted admin user. This vulnerability does not increase the privilege level of the user, but rather bypasses any CLI command restrictions by allowing full access to the shell. This issue affects Juniper Networks Junos OS Evolved: All versions prior to 20.4R3-S1-EVO; All versions of 21.1-EVO and 21.2-EVO.

Patch / fix

fixed in 1

Juniper Networks Junos OS Evolved 20.4R3-S1-EVO

Exploit prediction

0.87% chance of exploitation in the next 30 days, higher than 59% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.1	7.8	CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
NVD	2.0	7.2	AV:L/AC:L/Au:N/C:C/I:C/A:C

Affected products

Juniper Networks Junos OS Evolved

Classification

Weakness

CWE-77 Improper Neutralization of Special Elements used in a Command
CWE-78 Improper Neutralization of Special Elements used in an OS Command

References

kb.juniper.net /JSA11221
vendor-advisory

Sources

CVE List CVE-2021-31356
NVD CVE-2021-31356

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Summary