CVE-2026-49973Public exploitNetwork attack vectorHinoki check available

Unauthenticated ownership takeover via ungated password bootstrap

Published Jun 11, 2026 · Updated Jun 11, 2026

Missing authentication in Hermes WebUI before 0.51.358 allows remote attackers to claim a passwordless instance through POST /api/settings. While authentication is disabled, the handler accepts _set_password without a session and saves the resulting password hash while issuing a session cookie. Exploitation requires network reachability before initial setup finishes; success transfers WebUI ownership and locks out the intended operator until state is reset.

CVSS severity9.2
Critical
EPSS probability0.54%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

Missing authentication in Hermes WebUI before 0.51.358 allows remote attackers to claim a passwordless instance through POST /api/settings. While authentication is disabled, the handler accepts _set_password without a session and saves the resulting password hash while issuing a session cookie. Exploitation requires network reachability before initial setup finishes; success transfers WebUI ownership and locks out the intended operator until state is reset.

The record

CVE
CVE-2026-49973
Published
Jun 11, 2026
Updated
Jun 11, 2026
Vendor
Nathan Esquenazi
Product
Hermes WebUI
Classifications
CWE-306, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 11, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 11, 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 <0.51.358

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Nathan Esquenazi · Hermes WebUIversion=0 <0.51.358

Published CVSS scores

9.2VulnCheckCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:L/SC:N/SI:N/SA:N
9.4VulnCheckCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-306Missing Authentication for Critical Function
T1190Exploit Public-Facing Application

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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