What’s Vulnerable › Vulnerabilities
CVE-2022-26531
- Severity: high (CVSS 7.8 v3.1)
- Exploited in the wild: not listed in CISA KEV
- EPSS: 6.2% probability of exploitation in the next 30 days
- Public exploit or detection template: none known
- Published: 2022-05-24 · updated 2026-06-17
- Weakness: CWE-20
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.
Affected products
- Zyxel Atp100 Firmware: from 4.32 through 5.21
- Zyxel Atp100W Firmware: from 4.32 through 5.21
- Zyxel Atp200 Firmware: from 4.32 through 5.21
- Zyxel Atp500 Firmware: from 4.32 through 5.21
- Zyxel Atp700 Firmware: from 4.32 through 5.21
- Zyxel Atp800 Firmware: from 4.32 through 5.21
- Zyxel NAP203 firmware: through 6.25\(abfa.7\)
- Zyxel Nap303 Firmware: through 6.25\(abex.7\)
- Zyxel Nap353 Firmware: through 6.25\(abey.7\)
- Zyxel Nsg100 Firmware: from 1.00 before 1.33; 1.33, 1.33-patch1, 1.33-patch2, 1.33-patch3, 1.33-patch4 — fixed in 1.33
- Zyxel Nsg300 Firmware: from 1.00 before 1.33; 1.33, 1.33-patch1, 1.33-patch2, 1.33-patch3, 1.33-patch4 — fixed in 1.33
- Zyxel Nsg50 Firmware: from 1.00 before 1.33; 1.33, 1.33-patch1, 1.33-patch2, 1.33-patch3, 1.33-patch4 — fixed in 1.33
- Zyxel NWA110AX firmware: through 6.30\(abtg.2\)
- Zyxel Nwa1123-Ac-Hd Firmware: through 6.25\(abin.6\)
- Zyxel Nwa1123-Ac-Pro Firmware: through 6.25\(abhd.7\)
- Zyxel NWA1123ACv3 firmware: through 6.30\(abvt.2\)
- Zyxel Nwa1302-Ac Firmware: through 6.25\(abku.6\)
- Zyxel Nwa210Ax Firmware: through 6.30\(abtd.2\)
- Zyxel NWA50AX firmware: through 6.25\(abyw.5\)
- Zyxel Nwa5123-Ac-Hd Firmware: through 6.25\(abim.6\)
- Zyxel Nwa55Axe Firmware: through 6.25\(abzl.5\)
- Zyxel Nwa90Ax Firmware: through 6.27\(accv.2\)
- Zyxel NXC2500 firmware: through 6.10\(aaig.3\)
- Zyxel NXC5500 firmware: through 6.10\(aaos.3\)
- Zyxel Usg200 Firmware: from 4.09 through 4.71
- Zyxel Usg20 Firmware: from 4.09 through 4.71
- Zyxel Usg210 Firmware: from 4.09 through 4.71
- Zyxel Usg2200 Firmware: from 4.09 through 4.71
- Zyxel Usg300 Firmware: from 4.09 through 4.71
- Zyxel Usg310 Firmware: from 4.09 through 4.71
How to fix
Upgrade to a fixed version: Zyxel Nsg100 Firmware 1.33; Zyxel Nsg300 Firmware 1.33; Zyxel Nsg50 Firmware 1.33. Check the vendor advisory for mitigations.
References
- 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
- 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
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