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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.

PUBLISHED Reserved 2026-06-16 | Published 2026-06-17 | Updated 2026-06-17 | Assigner VulnCheck




CRITICAL: 9.1CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

CRITICAL: 9.1CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Problem types

Missing Authentication for Critical Function

Product status

Default status
unaffected

Any version before 0.51.409
affected

0.51.409 (semver)
unaffected

Credits

Chia Min Jun Lennon finder

References

github.com/nesquena/hermes-webui/releases/tag/v0.51.442 (Release Notes) release-notes

github.com/nesquena/hermes-webui/pull/4171 (Researcher Pull Request) technical-description

github.com/nesquena/hermes-webui/pull/4267 (Maintainer Pull Request) issue-tracking

github.com/...ommit/4d90577e25d5537cb07290eca3fb8abff3bab316 (Patch Commit) patch

www.vulncheck.com/...-registration-via-authentication-bypass third-party-advisory

cve.org (CVE-2026-55196)

nvd.nist.gov (CVE-2026-55196)

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