CVE-2026-21915: juniper networks jsi lwc Permissive List of Allowed Inputs

Vulnerability summary

CVE-2026-21915 is a high (CVSS 8.4) Permissive List of Allowed Inputs vulnerability in juniper networks jsi lwc. EPSS estimates a 2.24% chance of exploitation in the next 30 days, higher than 82.5% of scored vulnerabilities.

Timeline

1. 09-04-2026
   PublishedVulnerability first disclosed.
2. 13-04-2026
   Last modifiedVulnerability information updated.

Description

A Permissive List of Allowed Input vulnerability in the CLI of Juniper Networks Support Insights (JSI) Virtual Lightweight Collector (vLWC) allows a local, high privileged attacker to escalate their privileges to root. The CLI menu accepts input without carefully validating it, which allows for shell command injection. These shell commands are executed with root permissions and can be used to gain complete control of the system. This issue affects all JSI vLWC versions before 3.0.94.

• CWE-183Permissive List of Allowed InputsThe product implements a protection mechanism that relies on a list of inputs (or properties of inputs) that are explicitly allowed by policy because the inputs are assumed to be safe, but the list is too permissive - that is, it allows an input that is unsafe, leading to resultant weaknesses.
• CWE-78Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')The product constructs all or part of an OS command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended OS command when it is sent to a downstream component.