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.
https://github.com/nesquena/hermes-webui/releases/tag/v0.51.442
https://github.com/nesquena/hermes-webui/pull/4267
https://github.com/nesquena/hermes-webui/pull/4171
https://github.com/nesquena/hermes-webui/commit/4d90577e25d5537cb07290eca3fb8abff3bab316
Published: 2026-06-17
Updated: 2026-06-23
Base Score: 9.4
Vector: CVSS2#AV:N/AC:L/Au:N/C:C/I:C/A:N
Severity: High
Base Score: 9.1
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Severity: Critical
Base Score: 9.1
Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
Severity: Critical
EPSS: 0.00579