---
id: CVE-2026-55205
title: >-
  Hermes WebUI before 0.51.468 contains a resource exhaustion vulnerability in
  the unauthenticated POST /api/onboarding/oauth/start endpoint that allows
  unbounded accumulation of in-memory flow state and daemon threads
summary: >-
  Hermes WebUI before 0.51.468 contains a resource exhaustion vulnerability in
  the unauthenticated POST /api/onboarding/oauth/start endpoint that allows
  unbounded accumulation of in-memory flow state and daemon threads. Attackers
  can send …
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'
cwe:
  - CWE-770
vendor: nesquena
product: hermes-webui
affected:
  - hermes-webui < 0.51.468
published: '2026-06-18'
updated: '2026-09-17'
sourceUpdated: '2026-09-17T18:16:49.510'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-55205'
references:
  - url: >-
      https://github.com/nesquena/hermes-webui/commit/ce272d9cd5f8e5a4521278f56eb5388010901646
    label: disclosure@vulncheck.com
  - url: 'https://github.com/nesquena/hermes-webui/pull/3970'
    label: disclosure@vulncheck.com
  - url: 'https://github.com/nesquena/hermes-webui/pull/4338'
    label: disclosure@vulncheck.com
  - url: 'https://github.com/nesquena/hermes-webui/releases/tag/v0.51.468'
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/hermes-webui-resource-exhaustion-via-unauthenticated-oauth-flow-endpoint
    label: disclosure@vulncheck.com
  - url: 'https://github.com/nesquena/hermes-webui/pull/3970'
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
tags:
  - nvd
  - cve.org
  - exploit-available
exploitAvailable: true
ssvc:
  exploitation: poc
  automatable: 'yes'
  technicalImpact: partial
  timestamp: '2026-06-18T17:36:03.154710Z'
epss: 0.00524
epssPercentile: 0.42002
ingestedAt: '2026-09-17T18:25:15.970Z'
---

## Overview

Hermes WebUI before 0.51.468 contains a resource exhaustion vulnerability in the unauthenticated POST /api/onboarding/oauth/start endpoint that allows unbounded accumulation of in-memory flow state and daemon threads. Attackers can send repeated or concurrent requests to exhaust server memory and thread resources, potentially triggering repeated outbound device-code requests to upstream OAuth providers.

## Remediation

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