CVE-2026-20797: Copeland Xweb 300d Pro Firmware

Critical severity, CVSS 9.8. EPSS: 0.8% chance of exploitation in the next 30 days.

A stack based buffer overflow exists in an API route of XWEB Pro version 1.12.1 and prior, enabling unauthenticated attackers to cause stack corruption and a termination of the program.

Affected products

• Copeland Xweb 300d Pro Firmware: up to and including 1.12.1
• Copeland Xweb 500b Pro Firmware: up to and including 1.12.1
• Copeland Xweb 500d Pro Firmware: up to and including 1.12.1

Published 2026-02-27. Last modified 2026-06-17.