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HIGH severity

CVE-2026-119127 — Zitadel

HIGH

CVE-2026-119127 is a high-severity (CVSS 8.1) CWE-640 vulnerability. No vendor fix is recorded yet; mitigation options are listed below.

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…

Published
Updated
Affected
—
Patched
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Exploits
None indexed
Exploitation data as of Oct 29, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Description

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.

Detection & mitigation playbook

Vulnerability

  1. Detect

    Identify every host running the affected component and compare the installed build against the fixed version below — for source-built or distro-packaged software the version string, not a lockfile, is the source of truth (`dpkg -l`, `rpm -q`, or the binary's own `--version`).

  2. Remediation status

    No fixed release is recorded for CVE-2026-119127 yet. Track the upstream advisory, and apply the exposure-reduction steps below in the meantime.

  3. Mitigate without a patch

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Frequently Asked Questions

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.
O3 Security · Impact-Aware SCA

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CVE-2026-119127: Zitadel (High 8.1)