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Vulnerability record · CVE-2022-26531 · published 24 May 2022

CVE-2022-26531: Zyxel vpn100 firmware improper input validation vulnerability

Zyxel · Vpn100 Firmware

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.

7.8 CVSS 3.1 High EPSS 6.2% · top 6.7% CWE-20 · Improper input validation
7.8CVSS 3.1 base score, v2 4.6
6.2%EPSS exploitation probability, 30 days
NoNot in CISA KEV
65Affected product versions listed by NVD
8References
17 Jun 2026Last modified by NVD

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.

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected products

65 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
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
http://seclists.org/fulldisclosure/2022/Jun/15
https://www.zyxel.com/support/multiple-vulnerabilities-of-firewalls-AP-controllers-and-APs.shtml Vendor Advisory
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
http://seclists.org/fulldisclosure/2022/Jun/15
https://www.zyxel.com/support/multiple-vulnerabilities-of-firewalls-AP-controllers-and-APs.shtml Vendor Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2022-26531), CISA KEV, FIRST EPSS (scores of 2026-09-28). This page is refreshed as NVD updates the record.