CVE-2021-31356 Junos OS Evolved: Multiple shell-injection vulnerabilities in EVO UI wrapper scripts
Authenticated attackers can bypass CLI restrictions to execute arbitrary shell commands on Juniper Junos OS Evolved devices.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2021-31356?
CVE-2021-31356 is a high-severity command injection vulnerability in Juniper Junos Os Evolved, published on 19 Oct 2021. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
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.
Which versions are affected by CVE-2021-31356?
It affects 1 product.
Products include Juniper Junos Os Evolved.
How do I fix CVE-2021-31356?
No fix has been published for CVE-2021-31356 yet. Limit exposure of the affected software until one is available.
Upgrade, and pass arguments to programs as a list instead of through a shell. More about Command injection.
Is CVE-2021-31356 being exploited?
There is no known exploitation of CVE-2021-31356 in the wild and no public exploit code.
Other vulnerabilities in Juniper Junos Os Evolved
- CVE-2026-21902 Junos OS Evolved: PTX Series: A vulnerability allows a unauthenticated, network-based attacker to execute code as root
- CVE-2023-28983 Junos OS Evolved: Shell Injection vulnerability in the gNOI server
- CVE-2025-21599 Denial of service in Junos OS Evolved
- CVE-2024-47502 Junos OS Evolved: TCP session state is not always cleared on the Routing Engine leading to DoS
- CVE-2024-39531 Junos OS Evolved: ACX 7000 Series: Protocol specific DDoS configuration affects other protocols
Sources
Also known as GHSA-fr6c-hwr9-4gr5.