CVE-2026-31985: N2OS TUI Information Disclosure Flaw

CVE-2026-31985 Overview

CVE-2026-31985 affects the Nozomi Networks Remote Collector when configured through the n2os-tui interface. The generated configuration disables Transport Layer Security (TLS) certificate verification for connections to the upstream Guardian or Central Management Console (CMC). No option exists in the interface to enable verification. Attackers positioned on the network path can perform man-in-the-middle (MITM) attacks against these communications. Successful interception exposes the sync token, allows server impersonation, permits injection of spoofed asset data or vulnerability findings, and enables disruption of data flow between the Remote Collector and its upstream Guardian or CMC. The weakness is tracked under [CWE-671] (Lack of Administrator Control over Security).

Critical Impact
An attacker on the network can intercept Remote Collector traffic, steal the sync token, and inject falsified telemetry into Guardian or CMC.

Affected Products

Nozomi Networks Remote Collector configured via n2os-tui
Nozomi Networks Guardian (as upstream target)
Nozomi Networks Central Management Console (CMC) (as upstream target)

Discovery Timeline

2026-07-09 - CVE-2026-31985 published to NVD
2026-07-09 - Last updated in NVD database

Technical Details for CVE-2026-31985

Vulnerability Analysis

The n2os-tui configuration utility generates a Remote Collector configuration that omits TLS certificate validation for the outbound connection to the upstream Guardian or CMC. The interface does not expose a toggle or field to enforce validation. As a result, the collector accepts any TLS certificate presented by a peer claiming to be the Guardian or CMC, including self-signed or attacker-controlled certificates. This defeats the trust guarantees TLS is intended to provide on the transport channel.

An attacker with a network position between the Remote Collector and the upstream server can terminate the collector's TLS session and open a second TLS session to the legitimate Guardian or CMC. This classic MITM pattern gives the attacker plaintext visibility into the sync token used to authenticate the collector. With the token, the attacker can impersonate the collector against the Guardian or CMC, or impersonate the Guardian or CMC against other collectors.

Root Cause

The root cause is an insecure default in the configuration generator combined with the absence of an administrator control to enable certificate verification. Administrators cannot correct the behavior from the supported interface. The vulnerability falls under [CWE-671] because the missing control prevents operators from enforcing a stronger security posture.

Attack Vector

Exploitation requires network adjacency on any hop between the Remote Collector and its upstream Guardian or CMC. Techniques include Address Resolution Protocol (ARP) spoofing on shared segments, rogue gateway insertion, Border Gateway Protocol (BGP) hijacking on wide-area paths, or compromise of intermediate network devices. Once traffic is intercepted, the attacker can passively harvest the sync token or actively rewrite telemetry payloads. Injected data can create false asset inventories, fabricate vulnerabilities, or hide genuine indicators from operators monitoring the Guardian or CMC.

No verified proof-of-concept code is publicly available. See the Nozomi Networks Security Advisory for vendor-supplied technical details.

Detection Methods for CVE-2026-31985

Indicators of Compromise

Unexpected TLS certificate fingerprints presented to Remote Collectors when compared against the known Guardian or CMC certificate.
Duplicate or anomalous sync token usage originating from unexpected source addresses in Guardian or CMC access logs.
Sudden appearance of assets, vulnerabilities, or alerts in the Guardian or CMC that do not correlate with monitored network segments.

Detection Strategies

Capture packet metadata on segments carrying Remote Collector traffic and validate the server certificate hash against the expected Guardian or CMC certificate.
Baseline the volume, cadence, and asset identifiers submitted by each Remote Collector and alert on statistical deviations.
Correlate ARP tables, Media Access Control (MAC) address changes, and routing updates on paths between collectors and upstream servers to identify redirection attempts.

Monitoring Recommendations

Forward Guardian and CMC authentication logs and Remote Collector connection logs to a centralized data lake for retention and correlation.
Monitor for TLS handshakes on Remote Collector egress that terminate at addresses other than the sanctioned Guardian or CMC.
Track configuration file changes on Remote Collectors and alert when the TLS verification setting is altered outside of change windows.

How to Mitigate CVE-2026-31985

Immediate Actions Required

Apply the fixed Remote Collector release documented in the Nozomi Networks Security Advisory as soon as it is available in your environment.
Rotate the sync tokens used between Remote Collectors and their upstream Guardian or CMC after patching.
Restrict network paths between Remote Collectors and upstream servers to trusted, monitored segments using segmentation or dedicated management VLANs.

Patch Information

Consult the Nozomi Networks Security Advisory NN-2026:12-01 for the list of fixed versions and upgrade instructions for Remote Collector, Guardian, and CMC components.

Workarounds

Tunnel Remote Collector to Guardian or CMC traffic inside a mutually authenticated Internet Protocol Security (IPsec) or WireGuard tunnel to remove reliance on the collector's TLS validation.
Place Remote Collectors and their upstream servers on isolated management networks with strict access control lists to limit MITM opportunity.
Continuously verify the Guardian or CMC certificate fingerprint out-of-band and investigate any deviation immediately.

bash

# Example: restrict Remote Collector egress to the Guardian IP only
iptables -A OUTPUT -p tcp -d <GUARDIAN_IP> --dport 443 -j ACCEPT
iptables -A OUTPUT -p tcp --dport 443 -j DROP