Hermes WebUI < 0.51.409 - Unauthenticated Passkey Registration via Authentication Bypass (CVE-2026-55196) | HOL Guard CVE

Critical · CVSS 9.1CVE-2026-55196

Hermes WebUI < 0.51.409 - Unauthenticated Passkey Registration via Authentication Bypass

Answer in brief

CVE-2026-55196 records a Critical severity (CVSS 9.1) vulnerability in Hermes WebUI < 0.51.409 - Unauthenticated Passkey Registration via Authentication Bypass. The current sources do not mark it as known exploited. The current feed maps hermes-webui/hermes-webui (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Jun 17, 2026Updated Sep 17, 2026Source checked Sep 17, 2026First seen by HOL Jun 23, 2026Material review Sep 17, 2026

Upstream Advisory

Key facts

Risk: Critical · CVSS 9.1
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Available

Why this deserves its current priority

CVSS is 9.1. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps hermes-webui/hermes-webui (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
hermes-webui/hermes-webuigeneric	>=0 <0.51.409	0.51.409

Recommended response

Check inventory. Check lockfiles and deployed manifests for hermes-webui/hermes-webui.
Review the reported fix. Update hermes-webui/hermes-webui to 0.51.409 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Jun 17, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 17, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Jun 23, 2026

Sources and claim methodology

Upstream source description

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.

Quoted source text, attributed separately from HOL analysis.