CVE-2026-16812 — Arista VeloCloud Orchestrator: OS Command Injection | CVSS 10.0 CRITICAL

CRITICAL

CVSS 10.0 CRITICAL  ·  EPSS N/A  ·  Arista VeloCloud Orchestrator

Severity Overview

Summary

VeloCloud Orchestrator (VCO) on-prem has a security issue where this issue may allow a remote attacker to access privileged internal functionality and impact the VCO host. Successful exploitation may compromise the confidentiality, integrity, and availability of the orchestrator and data managed by the orchestrator.

This functionality was intended to be for internal use only and is not intended to be remotely accessible.

Hosted and Dedicated versions of VCO have already been patched in advance of this notice going out.

This issue was discovered externally and is known to be actively exploited.

What the Attack Looks Like

How it works: Attacker-controlled input is passed directly to a system command without sanitization. The OS executes the injected commands with the privileges of the application process.

Analyst Takeaway

The attack is launched over the network (remotely exploitable without physical access) and no authentication is required. This vulnerability is already in CISA KEV, which means exploitation has been confirmed in the wild — treat this as active risk, not theoretical exposure. The CVSS score places this in critical territory, so internet-facing systems and high-value assets should be prioritized for immediate remediation or compensating controls. In parallel with patching, defenders should review external exposure, hunt for signs of exploitation, and validate whether compensating controls are in place for vulnerable assets.

Detection Guidance

• CWE-78 — OS Command Injection
  • Application and WAF logs: Search for shell metacharacters in request parameters: semicolons, pipes (|), ampersands (&), backticks, $(, %0a (URL-encoded newline), and their double-encoded variants.
  • Process telemetry: Hunt for shell interpreters (bash, sh, zsh, cmd.exe, PowerShell) spawned as direct children of the application or web server process. This parent-child chain is rarely legitimate and warrants immediate investigation.
  • Executed command patterns: After initial injection, attackers commonly run: id, whoami, uname -a (reconnaissance), followed by curl or wget to retrieve secondary payloads. Search process command-line telemetry for these sequences.
  • Sysmon / auditd: On Windows, Sysmon Event 1 with a web server parent spawning cmd.exe or PowerShell is high-fidelity. On Linux, auditd execve syscall records from the application user are key.

Recommended Actions

Immediate (0–24 Hours)

• Inventory: Identify all systems running Arista VeloCloud Orchestrator. Include production, staging, dev, and cloud environments — untracked instances are the most likely to remain unpatched.
• Validate internet-facing exposure: Determine which of the affected systems are reachable from the public internet. Prioritize these for immediate remediation or compensating controls.
• Apply compensating controls now: For systems that cannot be patched immediately, implement temporary mitigations: restrict access via firewall rules or ACLs, add WAF rules if applicable, disable or isolate the vulnerable component if feasible without breaking critical operations.

Remediation

• Apply the vendor patch: Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.
• CISA directive deadline: 2026-07-30 — this is the mandatory deadline for US federal civilian agencies under BOD 22-01. All organizations should treat this date as a strong target regardless of federal mandate.
• Verify remediation: After patching, confirm the correct version is installed on all affected hosts. Run a vulnerability scan or use your asset management tooling to verify — do not rely solely on change tickets.

Detection Coverage

• Unauthenticated exploitation monitoring: Because this vulnerability requires no authentication, internet-facing scanning and exploitation attempts may begin within hours of public disclosure. Ensure alerting is in place before the end of the day.
• Threat intelligence feeds: Monitor your TI feeds and vendor advisory channels for published indicators of compromise (IOCs), proof-of-concept exploit releases, or active campaign reporting associated with this CVE — these should trigger an immediate hunt even if no internal alerts have fired.

Detection Playbooks

Vulnerability Details

Additional Notes

https://www.arista.com/en/support/advisories-notices/security-advisory/24364-security-advisory-0144 ; BOD 26-04: https://www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk ; Forensics Triage Requirements: https://www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk ; https://nvd.nist.gov/vuln/detail/CVE-2026-16812