Auth bypass in Hermes-Webui
CVE-2026-55196
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.
Vulnerability class: Broken Authentication
Published · last modified .
CVSS v3 metric
CVSS v3 base score 9.1 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N.
EPSS exploit prediction
EPSS: 0.008 (55.6th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 56th percentile — 55.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.006 · newest: 0.008 · change: +0.002
Affected products
- Hermes-Webui — versions 0, 0.51.409
Weakness classification (CWE)
References
- github.com/nesquena/hermes-webui/releases/tag/v0.51.442 (release-notes)
- github.com/nesquena/hermes-webui/pull/4171 (issue-tracking, technical-description, patch)
- github.com/nesquena/hermes-webui/pull/4267 (issue-tracking, patch)
- github.com/nesquena/hermes-webui/commit/4d90577e25d5537cb07290eca3fb8abff3bab316 (patch)
- www.vulncheck.com/advisories/hermes-webui-unauthenticated-passkey-registration-… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-55196?
- CVE-2026-55196 is a critical-severity vulnerability in Hermes-Webui, classified under Missing Authentication for Critical Function. CVSS score: 9.1/10. Published 2026-06-17.
- How severe is CVE-2026-55196?
- Critical severity. CVSS v3 base score is 9.1 out of 10.