CVE-2026-42008Hinoki check available

Authentication bypass via trusted-proxy field injection

Published Aug 28, 2026 · Updated Aug 28, 2026

Authentication bypass in Open-Xchange OX Dovecot CE and Pro allows trusted-proxy hosts to authenticate as any user without a password. XCLIENT forwarding fails to namespace a bare proxy-supplied token separately from internal authentication fields, allowing nopassword field injection. Exposure requires a configured trusted proxy and a password database that honors the injected passwordless-authentication field.

CVSS severity4.3
Medium
EPSS probability0.19%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
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Summary

What happened

Authentication bypass in Open-Xchange OX Dovecot CE and Pro allows trusted-proxy hosts to authenticate as any user without a password. XCLIENT forwarding fails to namespace a bare proxy-supplied token separately from internal authentication fields, allowing nopassword field injection. Exposure requires a configured trusted proxy and a password database that honors the injected passwordless-authentication field.

The record

CVE
CVE-2026-42008
Published
Aug 28, 2026
Updated
Aug 28, 2026
Vendor
Open-Xchange GmbH
Product
OX Dovecot CE
Classifications
CWE-287, T1078
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 28, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 28, 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=2.3.4 <2.4.5

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

Open-Xchange GmbH · OX Dovecot CEversion=2.3.4 <2.4.5
Open-Xchange GmbH · OX Dovecot Proversion=2.3.4 <2.3.22.2; version=3.0.0 <3.0.7; version=3.1.0 <3.1.6

Published CVSS scores

4.3Open-Xchange GmbHCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

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)
Vectoradjacent
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-287Improper Authentication
T1078Valid Accounts

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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