# CVE-2026-56666: ZITADEL: Auto-linking by email: IdP-side email verification is not checked

> Attackers can take over victim accounts by linking permissive external IdP profiles to local accounts without proper email verification checks.

- **Severity:** Medium 4.8 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 10 Jul 2026
- **Updated:** 13 Jul 2026
- **Also known as:** GHSA-992q-9gwp-7r79, GO-2026-6470

## What is CVE-2026-56666?

CVE-2026-56666 is a medium-severity authentication bypass vulnerability in zitadel, published on 10 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

ZITADEL is an open source identity management platform. Prior to 4.15.3, ZITADEL's external identity provider handler checks that the local user's email is verified but does not verify that the external IdP confirmed ownership of the same email before auto-linking by email, allowing a permissive provider account with a victim email address to be linked to the victim's local account. This issue is fixed in version 4.15.3.

Weakness: CWE-287 (Improper Authentication)

## Which versions are affected by CVE-2026-56666?

3 open source packages ship an affected version, including github.com/zitadel/zitadel.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `github.com/zitadel/zitadel` | Go | All versions | None |
| `github.com/zitadel/zitadel` | Go | All versions | 4.15.3 |
| `github.com/zitadel/zitadel` | Go | All versions | 4.15.3 |

## How do I fix CVE-2026-56666?

Upgrade github.com/zitadel/zitadel to 4.15.3 or later.

## Is CVE-2026-56666 being exploited?

There is no known exploitation of CVE-2026-56666 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-56666 and fix it if it is affected.

What it is: CVE-2026-56666 is a medium-severity authentication bypass vulnerability in zitadel, published on 10 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-56666 in the wild and no public exploit code.

Affected packages and fixed versions:
- github.com/zitadel/zitadel (Go): affected all versions; no fix listed
- github.com/zitadel/zitadel (Go): affected all versions; fixed in 4.15.3
- github.com/zitadel/zitadel (Go): affected all versions; fixed in 4.15.3

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-56666/ (Markdown: https://insights.sbomify.com/CVE-2026-56666/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-56666
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-56666
- OSV: https://osv.dev/vulnerability/CVE-2026-56666

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-56666/
Summaries are generated and may contain mistakes; the official description above is the record.