CVE-2026-29191 — zitadel
CRITICALCVE-2026-29191 is a critical-severity (CVSS 9.3) Cross-site Scripting (XSS) vulnerability in github.com/zitadel/zitadel. A fix is available for github.com/zitadel/zitadel — see the affected versions and patch details below.
ZITADEL: 1-Click Account Takeover via XSS in /saml-post Endpoint
Exploitation Status
No confirmed exploitation observed yet
- A successful exploit gives an attacker total control of the affected component, not partial access.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-29191.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2026-29191 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,636 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
github.com/zitadel/zitadel🐹github.com/zitadel/zitadel/v2Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
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 could reset the password of their victims, and take over their accounts.
It's important to note that this specific attack vector is mitigated for accounts that have Multi-Factor Authentication (MFA) or Passwordless authentication enabled.
Affected Versions
Systems running one of the following versions are affected:
- 4.x:
4.0.0through4.11.1(including RC versions)
Important Note: Although this /saml-post endpoint is used when Zitadel is integrated with a SAML Identity Provider (IdP), the vulnerability in this finding does not require Zitadel to be configured with a SAML IdP. Consequently, Zitadel is vulnerable in its default, out-of-the-box configuration.
Patches
The vulnerability has been addressed in the latest releases. The patch reworked the integration of SAML IdPs and the /saml-post endpoint no longer exists. Additionally, the page to change the password, now always requires the user's current password regardless of the state of the authenticated session.
4.x: Upgrade to >= 4.12.0
Workarounds
The recommended solution is to upgrade to a patched version. If an upgrade is not possible and no SAML IdP integration is needed, a WAF or reverse proxy rule can be deployed to prevent access to the endpoint.
Questions
If there are any questions or comments about this advisory, please email them to [email protected]
Credits
ZITADEL extends thanks once again to Amit Laish from GE Vernova for finding and reporting the vulnerability.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/zitadel/zitadel | ≥ 4.0.0&&< 4.12.0 | 4.12.0go get github.com/zitadel/zitadel@v4.12.0 |
| 🐹Go | github.com/zitadel/zitadel/v2 | ≥ 4.0.0&&< 4.12.0 | 4.12.0go get github.com/zitadel/zitadel/v2@v4.12.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/zitadel/zitadel, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/zitadel/zitadel to 4.12.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-29191 is resolved across your whole dependency graph.
Workarounds
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.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-29191 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-29191. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-29191 in your dependencies?
O3 Security finds CVE-2026-29191 across Go dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.