Vulnerability · Published Sep 21, 2026 · Assigned by GitHub_M
CVE-2026-61628nginx ignition has Unauthenticated Admin Account Creation via Onboarding Race Condition
High 8.1
In plain English
A high-severity race condition in nginx-ignition from lucasdillmann. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 38% of all known vulnerabilities). Ready-made attack tooling exists: public proof-of-concept code. Fixed versions are available - upgrade the affected package.
Official description
nginx ignition is a user interface for the nginx web server. Prior to version 2.41.1, `POST /api/users/onboarding/finish` is registered as anonymous (unauthenticated) and creates a user with full ReadWrite admin permissions. Because the handler uses a check-then-act (TOCTOU) pattern between the "onboarding already completed?" check and the user-creation write, with no atomic guard, a remote unauthenticated attacker who can reach an instance in its pre-onboarding state can create an administrator account for themselves — and concurrent requests can create multiple admin accounts in a single race. Version 2.41.1 patches the issue.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Go | github.com/lucasdillmann/nginx-ignition | 0.0.0-20260621194639-0586b4e55ab | GHSA-pxcx-fv34-x9p5 |
| Go | github.com/lucasdillmann/nginx-ignition | no fix listed | GO-2026-6540 |
| Ubuntu:22.04:LTS | nginx | no fix listed | UBUNTU-CVE-2026-61628 |
| Ubuntu:24.04:LTS | nginx | no fix listed | UBUNTU-CVE-2026-61628 |
| Ubuntu:26.04:LTS | nginx | no fix listed | UBUNTU-CVE-2026-61628 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| lucasdillmann | nginx-ignition | < 2.41.1 |
Weakness: CWE-362 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H