---
id: CVE-2026-49955
title: Hermes WebUI < 0.51.270 Resource Exhaustion via passkey/options
summary: >-
  Hermes WebUI before version 0.51.270 contains a resource exhaustion
  vulnerability that allows unauthenticated remote attackers to degrade service
  availability by repeatedly calling the passkey options endpoint without
  completing assertio…
severity: medium
cvss: 5.3
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L'
cvssSource: cna
cwe:
  - CWE-770
vendor: nesquena
product: hermes-webui
affected:
  - hermes-webui < 0.51.270
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: partial
  timestamp: '2026-06-09T18:23:18.415312Z'
published: '2026-06-09'
updated: '2026-11-08'
sourceUpdated: '2026-11-08T14:04:57.528Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-49955'
references:
  - url: 'https://github.com/nesquena/hermes-webui/releases/tag/v0.51.270'
    label: hermes-webui 0.51.270 Release Notes
  - url: 'https://github.com/nesquena/hermes-webui/pull/3624'
  - url: 'https://github.com/nesquena/hermes-webui/pull/3674'
  - url: >-
      https://github.com/nesquena/hermes-webui/commit/58528a4d88b0fa4f7b822e31d6051c669769bd3b
  - url: >-
      https://www.vulncheck.com/advisories/hermes-webui-resource-exhaustion-via-passkey-options
tags:
  - cve.org
epss: 0.00586
epssPercentile: 0.48293
ingestedAt: '2026-11-08T14:51:22.382Z'
---

## Overview

Hermes WebUI before version 0.51.270 contains a resource exhaustion vulnerability that allows unauthenticated remote attackers to degrade service availability by repeatedly calling the passkey options endpoint without completing assertion. Attackers can send unlimited POST requests to the authentication endpoint, causing unbounded growth of the challenge store file and excessive CPU and disk I/O through repeated JSON file rewrites.

## Affected

- `hermes-webui < 0.51.270`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.