CVE-2021-40818: Glewlwyd SSO Server Project Glewlwyd SSO Server

Critical severity, CVSS 9.8. EPSS: 1.5% chance of exploitation in the next 30 days.

scheme/webauthn.c in Glewlwyd SSO server through 2.5.3 has a buffer overflow during FIDO2 signature validation in webauthn registration.

Affected products

• Glewlwyd SSO Server Project Glewlwyd SSO Server: up to and including 2.5.3

Published 2021-09-08. Last modified 2026-06-17.