Zitadel up to 4.19.4 Login V2 UI injection

Summaryinfo

A vulnerability classified as critical was found in Zitadel up to 4.19.4. Affected by this issue is some unknown functionality of the component Login V2 UI. Executing a manipulation of the argument x-zitadel-public-host/x-zitadel-forward-host/x-forwarded-host can lead to injection. This vulnerability appears as CVE-2026-119127. The attack may be performed from remote. There is no available exploit. Upgrading the affected component is advised.

Detailsinfo

A vulnerability has been found in Zitadel up to 4.19.4 and classified as critical. This vulnerability affects an unknown function of the component Login V2 UI. The manipulation of the argument x-zitadel-public-host/x-zitadel-forward-host/x-forwarded-host 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. CVE summarizes:

ZITADEL 4.0.0 before 4.19.5 contains a host header injection vulnerability in the Login V2 UI that allows unauthenticated attackers to poison password-reset, invite, and email-verification links by supplying untrusted x-zitadel-public-host, x-zitadel-forward-host, or x-forwarded-host headers. Attackers knowing a victim's login name can point the links in genuine emails at their host, harvest the single-use codes when the links are opened, and take over accounts including instance administrators.

The advisory is available at github.com. This vulnerability was named CVE-2026-119127 since 10/29/2026. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. Successful exploitation requires user interaction by the victim. Technical details are known, but there is no available exploit. This vulnerability is assigned to T1055 by the MITRE ATT&CK project.

Upgrading to version 4.19.5 eliminates this vulnerability.

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Productinfo

Name

• Zitadel

Version

• 4.19.0
• 4.19.1
• 4.19.2
• 4.19.3
• 4.19.4

Website

• Product: https://github.com/zitadel/zitadel/

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