How severe is CVE-2026-55196?

CVE-2026-55196 has a CVSS 3.x base score of 9.1, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.

Is CVE-2026-55196 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (43rd percentile), an estimate of the probability of exploitation in the next 30 days.

How do I fix CVE-2026-55196?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

Does CVE-2026-55196 have an EU (EUVD) identifier?

Yes. CVE-2026-55196 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-37777.

When was CVE-2026-55196 published?

CVE-2026-55196 was published on 2026-06-17 and last updated on 2026-06-23.

CVE-2026-55196

CVE-2026-55196 is a critical-severity vulnerability with a CVSS 3.x base score of 9.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-306.

Key facts

Severity: Critical (CVSS 3.x base score 9.1)
CVSS v4: 9.1
EPSS exploit prediction: 1% (43rd percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-37777
Weakness: CWE-306
Published: 2026-06-17
Last modified: 2026-06-23

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.

Frequently asked questions

What is 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.
How severe is CVE-2026-55196?: CVE-2026-55196 has a CVSS 3.x base score of 9.1, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.
Is CVE-2026-55196 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (43rd percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2026-55196?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
Does CVE-2026-55196 have an EU (EUVD) identifier?: Yes. CVE-2026-55196 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-37777.
When was CVE-2026-55196 published?: CVE-2026-55196 was published on 2026-06-17 and last updated on 2026-06-23.

References

Other CWE-306 (Missing Authentication for Critical Function) vulnerabilities

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CVE-2026-49257 — Critical (CVSS 10.0): mcp-pinot is a Python-based Model Context Protocol (MCP) server for interacting with Apache Pinot. In versions 3.0.1…
CVE-2026-46846 — Critical (CVSS 10.0): Vulnerability in the Oracle WebCenter Portal product of Oracle Fusion Middleware (component: Security Framework).…
CVE-2026-46803 — Critical (CVSS 10.0): Vulnerability in the Oracle WebCenter Portal product of Oracle Fusion Middleware (component: Security Framework).…
CVE-2026-46800 — Critical (CVSS 10.0): Vulnerability in the Oracle WebCenter Sites product of Oracle Fusion Middleware (component: WebCenter Sites).…

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