Raw vector
CVSS:4.0/AV:L/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:U/V:X/RE:M/U:XSummary
CVE-2026-21915 is a high-severity Permissive List of Allowed Inputs (CWE-183) vulnerability in Juniper Virtual Lightweight Collector. Its CVSS base score is 8.4 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Command and Scripting Interpreter (T1059); ranked in the top 19% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified map to SA-11 (Developer Testing and Evaluation) and SI-10 (Information Input Validation) — see the control section below for these in your framework.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-21078
Vulnerability Data
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…
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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(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
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Mitigating Controls (NIST 800-53 r5) AI
Developer testing and evaluation can discover missing or incorrect command sanitization during development.
Strict validity checks on inputs directly stop overly permissive allow lists from being used as the protection mechanism.
Least privilege reduces the permissions available to any process that could be subverted by injected commands.
Least functionality restricts available OS commands and interpreters, limiting the blast radius of injection.
Secure engineering principles require proper neutralization of untrusted input before command construction.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Secure SDLC practices directly require rigorous allow-list design and testing that prevents permissive input validation.
Routine patching/maintenance can remediate known command-injection CVEs in dependencies (partial forward) but does nothing to stop developers from introducing improper neutralization in custom code (none reverse).
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Security testing can detect overly broad allow-lists, but does not inherently prevent their creation.
Application security requirements can mandate strict, minimal allow-lists and input validation rules that prevent overly permissive lists.
Secure system architecture and engineering principles require explicit, least-privilege input validation designs that directly address permissive allow-lists.
Secure coding standards enforce rigorous input validation and reject unsafe values, mitigating permissive allow-list weaknesses.
Configuration management can enforce validated input rules, yet does not directly address the design flaw of permissive lists.