# CVE-2026-19607: Keycloak-services: keycloak-services: broker-originated username collision causes account lockout

> Attackers can lock out legitimate users by registering a colliding username on an external identity provider, disrupting access to Keycloak accounts.

- **Severity:** Medium 5.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 16 Sep 2026
- **Updated:** 16 Sep 2026
- **Also known as:** GHSA-h87q-rx56-87wm, UBUNTU-CVE-2026-19607

## What is CVE-2026-19607?

CVE-2026-19607 is a medium-severity authentication bypass vulnerability in Red Hat Single Sign-On 7, published on 16 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A flaw was found in the first-broker-login flow of the keycloak-services component. This component handles the initial authentication and account linking when a user logs in via an external identity provider. The issue allows an attacker to register a matching username on an external provider to trigger a collision in Keycloak, which results in the legitimate user being locked out of their account.

Weakness: CWE-287 (Improper Authentication)

## Which versions are affected by CVE-2026-19607?


## How do I fix CVE-2026-19607?

No fix has been published for CVE-2026-19607 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-19607 being exploited?

There is no known exploitation of CVE-2026-19607 in the wild and no public exploit code.

Public exploit code:

- Vulnerability Details and Exploit for CVE-2026-19607 (github_poc): https://github.com/7Ragnarok7/CVE-2026-19607

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-19607 and fix it if it is affected.

What it is: CVE-2026-19607 is a medium-severity authentication bypass vulnerability in Red Hat Single Sign-On 7, published on 16 Sep 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-2026-19607 in the wild and no public exploit code.

Affected product: Red Hat Single Sign-On 7. No package-level version data is available, so check the vendor advisory linked from the reference page.

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-2026-19607/ (Markdown: https://insights.sbomify.com/CVE-2026-19607/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-19607
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-19607
- OSV: https://osv.dev/vulnerability/CVE-2026-19607

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-19607/
Summaries are generated and may contain mistakes; the official description above is the record.