CVE-2026-33921 Nozomi Networks CVE debrief

Who should care

Administrators and users of systems where Npcap is installed, especially those concerned with network security and data privacy, should be aware of this vulnerability. They should verify Npcap installation and configuration to ensure secure access restrictions are applied. Additionally, they should monitor network traffic for suspicious activity and consider updating Npcap to the latest version if available. This vulnerability may impact organizations that rely on Npcap for network traffic capture and analysis, particularly those with sensitive information on their networks.

Technical summary

The Npcap driver, deployed by the Windows installer, has an insecure default access restriction setting. This allows any local user, without administrative privileges, to capture and send raw packets on the network segment. The vulnerability exposes information from the host and other systems on the same network segment. The issue arises from the installer's failure to restrict access to the driver, leaving it accessible to every local user. This vulnerability can be mitigated by ensuring secure access restrictions are applied to the Npcap driver.

Defensive priority

Local privilege escalation vulnerability in Npcap driver allows unauthorized network traffic capture and manipulation.

Recommended defensive actions

• Verify Npcap installation and configuration to ensure secure access restrictions are applied.
• Restrict Npcap driver access to administrators only.
• Monitor network traffic for suspicious activity.
• Update Npcap to the latest version if available.
• 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.

Evidence notes

The Windows installer for Npcap sets insecure default access restrictions, allowing local users to capture and send network traffic. Official CVE and NVD records provide details. The vulnerability allows unauthorized access to network traffic, potentially disclosing sensitive information. Defenders should verify Npcap installation and configuration, ensuring secure access restrictions are applied. They should also monitor network traffic for suspicious activity and consider updating Npcap to the latest version if available. Additionally, defenders should be aware of the potential for local users to exploit this vulnerability, especially in environments where Npcap is widely used.

Sources and 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.