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Critical, CVSS 9.3

ZITADEL has 1-Click Account Takeover via XSS in /saml-post Endpoint

CVE-2026-29191GHSA-pr34-2v5x-6qjq

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (github.com/zitadel/zitadel 4.12.0; github.com/zitadel/zitadel/v2 4.12.0), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
9.3 · CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N
EPSS
  • CVE-2026-29191: 0.46% estimated exploitation activity in the next 30 days; percentile 39.54 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

Summary A vulnerability was discovered in Zitadel's login V2 interface that allowed a possible account takeover. Impact Zitadel exposes an HTTP endpoint named /saml-post. This endpoint is used for handling requests to SAML IdPs and accepts two HTTP GET parameters: url and id. When these parameters are supplied, users’ browsers auto-submit an HTTP POST request to the provided url parameter. The endpoint insecurely redirects users using the provided url GET parameter. As a result, by specifying a javascript: scheme, malicious JS code could be executed on Zitadel users’ browsers. The endpoint also reflects user-supplied input in the server response, without HTML-encoding it. As a result, it is possible to inject arbitrary HTML code, which again leads to malicious JS code execution in the Zitadel users’ browsers. An unauthenticated remote attacker can exploit these XSS vulnerabilities, and thus, execute malicious JavaScript code on behalf of Zitadel users. By doing so, such an attacker…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 1 · created ·

    Published from ghsa record GHSA-pr34-2v5x-6qjq

Agent brief

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# Patch Next advisory brief: CVE-2026-29191

Advisory: ZITADEL has 1-Click Account Takeover via XSS in /saml-post Endpoint
IDs: CVE-2026-29191, GHSA-pr34-2v5x-6qjq
Record: https://patchnext.com/advisories/cve-2026-29191 (revision 1, source checked 26 Oct 2026, 15:15 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Critical (CVSS 9.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/zitadel/zitadel 4.12.0; github.com/zitadel/zitadel/v2 4.12.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/zitadel/zitadel: affected >= 4.0.0, < 4.12.0; fixed in 4.12.0
- Go github.com/zitadel/zitadel/v2: affected >= 4.0.0, < 4.12.0; fixed in 4.12.0

## Suggested inspection (read-only)
- Go github.com/zitadel/zitadel: check the installed version with your package manager.
- Go github.com/zitadel/zitadel/v2: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/zitadel/zitadel, github.com/zitadel/zitadel/v2.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-pr34-2v5x-6qjq (GitHub-reviewed advisory GHSA-pr34-2v5x-6qjq lists affected ranges: Go github.com/zitadel/zitadel >=4.0.0 =4.0.0 <4.12.0)

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