Ref# ADV2026_192 | Date: Mar 30th 2026

---

WatchGuard published a security advisory highlighting vulnerabilities in the following products on March 26, 2026. It is recommended that you take the necessary precautions by ensuring your products are always updated. 

• Fireware OS – versions prior to 2026.2 

• Fireware OS – versions prior to 12.12 

 

For more information on these updates, you can follow these URLs: 

• WatchGuard Firebox Insecure Deserialization in Fireware Access Portal (CVE-2026-4266) 

• WatchGuard Security Advisories 

 

The Guyana National CIRT recommends that users and administrators review these updates and apply them where necessary. 

 PDF Download: WatchGuard_Security_Advisory

References 

• WatchGuard Firebox Insecure Deserialization in Fireware Access Portal (CVE-2026-4266). (March 26, 2026). Retrieved from WatchGuard. https://www.watchguard.com/wgrd-psirt/advisory/wgsa-2026-00007 

 

• WatchGuard Security Advisories. (n.b.). Retrieved from WatchGuard. https://www.watchguard.com/wgrd-psirt/advisories 

 

• WatchGuard security advisory. (March 27, 2026). Retrieved from Canadian Centre for Cyber Security. https://www.cyber.gc.ca/en/alerts-advisories/watchguard-security-advisory-av26-289