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CVE-2026-21915 Juniper CVE debrief

A high privileged local attacker can escalate privileges to root via shell command injection in Juniper Networks Support Insights (JSI) Virtual Lightweight Collector (vLWC) due to a permissive list of allowed input in the CLI. The CLI menu accepts input without careful validation, allowing for shell command injection with root permissions. This vulnerability affects all JSI vLWC versions before 3.0.94, and system administrators should take immediate action to upgrade to prevent potential privilege escalation attacks.

Vendor
Juniper
Product
Virtual Lightweight Collector
CVSS
HIGH 8.4
CISA KEV
Not listed in stored evidence
Original CVE published
2026-04-09
Original CVE updated
2026-07-08
Advisory published
2026-04-09
Advisory updated
2026-07-08

Who should care

System administrators and security teams responsible for Juniper Networks Support Insights (JSI) Virtual Lightweight Collector (vLWC) should be aware of this vulnerability and take immediate action to upgrade to version 3.0.94 or later to prevent potential privilege escalation attacks.

Technical summary

The CVE-2026-21915 vulnerability is caused by a permissive list of allowed input in the CLI of Juniper Networks Support Insights (JSI) Virtual Lightweight Collector (vLWC). This allows a local, high privileged attacker to escalate their privileges to root by injecting shell commands. The CLI menu does not carefully validate input, enabling shell command injection with root permissions. This issue affects all JSI vLWC versions before 3.0.94.

Defensive priority

High priority should be given to upgrading Juniper Networks Support Insights (JSI) Virtual Lightweight Collector (vLWC) to version 3.0.94 or later to prevent potential privilege escalation attacks.

Recommended defensive actions

  • Upgrade Juniper Networks Support Insights (JSI) Virtual Lightweight Collector (vLWC) to version 3.0.94 or later.
  • Implement additional monitoring and logging to detect potential privilege escalation attempts.
  • Review and restrict access to the CLI to minimize the attack surface.
  • Review compensating controls for exposed systems while remediation is scheduled and verified.
  • Check relevant monitoring, detection, and logs for exposed assets that need extra review.
  • Track exceptions, retest remediated assets, and close the item only after evidence is documented.
  • Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up.

Evidence notes

The CVE record was published on 2026-04-09T22:16:24.747Z and was last modified on 2026-07-08T03:19:23.710Z. The NVD entry is currently Analyzed. The vulnerability has a CVSS score of 8.4 and a severity of HIGH.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-21915 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-21915

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-21915 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-21915

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.