CVE-2026-55205Public exploitNetwork attack vector

Unauthenticated service degradation via unbounded OAuth flows

Published Jun 18, 2026 · Updated Jun 18, 2026

Resource exhaustion in Hermes WebUI before 0.51.468 allows remote attackers to degrade service via unauthenticated OAuth-start requests. The OAuth start path creates pending flows and daemon polling workers without atomically checking and reserving provider/profile keys. Network access to the endpoint is sufficient; repeated or concurrent requests consume memory and threads and multiply upstream device-code requests.

CVSS severity6.9
Medium
EPSS probability0.52%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Resource exhaustion in Hermes WebUI before 0.51.468 allows remote attackers to degrade service via unauthenticated OAuth-start requests. The OAuth start path creates pending flows and daemon polling workers without atomically checking and reserving provider/profile keys. Network access to the endpoint is sufficient; repeated or concurrent requests consume memory and threads and multiply upstream device-code requests.

The record

CVE
CVE-2026-55205
Published
Jun 18, 2026
Updated
Jun 18, 2026
Vendor
Nathan Esquenazi
Product
Hermes WebUI
Classifications
CWE-770, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 18, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 18, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <0.51.468

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Nathan Esquenazi · Hermes WebUIversion=0 <0.51.468

Published CVSS scores

6.9VulnCheckCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
5.3VulnCheckCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-770Allocation of Resources Without Limits or Throttling
T1499Endpoint Denial of Service

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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