CVE-2026-55196: Hermes-Webui

Critical severity, CVSS 9.1. EPSS: 0.8% chance of exploitation in the next 30 days.

Hermes WebUI before 0.51.409 contains an authentication bypass vulnerability in passkey registration endpoints that allows unauthenticated remote attackers to register arbitrary passkeys. When HERMES_WEBUI_PASSKEY=1 is enabled with no existing credentials, POST /api/auth/passkey/register/options and POST /api/auth/passkey/register endpoints are accessible without authentication, allowing attackers to claim the first passkey and gain permanent administrative control.

Affected products

• Hermes-Webui Hermes-Webui: before 0.51.409 (fixed in 0.51.409)

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