Open-Xchange Dovecot Pro/Dovecot CE Trusted Proxy injection

Summaryinfo

A vulnerability marked as critical has been reported in Open-Xchange Dovecot Pro and Dovecot CE. This affects an unknown part of the component Trusted Proxy. This manipulation causes injection. This vulnerability appears as CVE-2026-42008. The attack may be initiated remotely. There is no available exploit.

Detailsinfo

A vulnerability was found in Open-Xchange Dovecot Pro and Dovecot CE (the affected version is unknown). It has been declared as critical. Affected by this vulnerability is an unknown code of the component Trusted Proxy. The manipulation with an unknown input leads to a injection vulnerability. The CWE definition for the vulnerability is CWE-74. The product constructs all or part of a command, data structure, or record using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify how it is parsed or interpreted when it is sent to a downstream component. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

Forwarding information received from a host listed as a trusted proxy is not kept separate from Dovecot's own authentication fields, so a value sent by that host can be injected as an internal authentication field. Any host permitted to act as a trusted proxy can authenticate as any user without knowing that user's password. This affects deployments whose password database honours a field that permits authentication without a password. Deployments that do not configure trusted proxies are not affected. Restrict the list of trusted proxy networks to hosts that are fully under your control. Update to non-vulnerable version. No publicly available exploits are known.

The advisory is shared at documentation.open-xchange.com. This vulnerability is known as CVE-2026-42008 since 04/23/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Neither technical details nor an exploit are publicly available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 08/28/2026). MITRE ATT&CK project uses the attack technique T1055 for this issue.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

The vulnerability is also documented in the vulnerability database at CERT Bund (WID-SEC-2026-3076). Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Affected

• Open Source Dovecot

Productinfo

Type

• Mail Server Software

Vendor

• Open-Xchange

Name

• Dovecot CE
• Dovecot Pro

License

• open-source

Website

• Vendor: https://www.open-xchange.com/

CPE 2.3info

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CPE 2.2info

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Sourcesinfo

Entryinfo

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Discussion