# CVE-2026-44476: Doorkeeper OpenID Connect: Dynamic Client Registration feature creates public clients with client_secret

> Attackers can authenticate as dynamically registered clients without a secret, bypassing authentication in Doorkeeper OpenID Connect when this feature is enabled.

- **Severity:** Medium 6.3 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 25 Aug 2026
- **Updated:** 26 Aug 2026
- **Also known as:** DEBIAN-CVE-2026-44476, GHSA-m6vc-f87m-cc2h, UBUNTU-CVE-2026-44476

## What is CVE-2026-44476?

CVE-2026-44476 is a medium-severity authentication bypass vulnerability in doorkeeper-gem doorkeeper-openid_connect, published on 25 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Doorkeeper is an OAuth 2 provider for Ruby on Rails. In version 1.9.0, an attacker who knows only a dynamically registered client's client_id, which is public information, can authenticate as that client at the token endpoint and obtain an access token without providing its client_secret. This occurs because the Dynamic Client Registration feature creates applications with confidential: false hard-coded, even though the registration response returns a client_secret and advertises support for the client_secret_basic and client_secret_post authentication methods; since Doorkeeper treats a blank or missing secret as valid for non-confidential (public) clients, the secret is never verified. Only projects that have explicitly enabled Dynamic Client Registration, which is disabled by default, are affected. This issue is fixed in version 1.10.0.

Weakness: CWE-287 (Improper Authentication), CWE-1390 (Weak Authentication)

## Which versions are affected by CVE-2026-44476?

2 open source packages ship an affected version, including doorkeeper-openid_connect.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `doorkeeper-openid_connect` | RubyGems | From 1.9.0 | 1.10.0 |
| `doorkeeper-openid_connect` | RubyGems | From 1.9.0 | 1.10.0 |

## How do I fix CVE-2026-44476?

Upgrade doorkeeper-openid_connect to 1.10.0 or later.

## Is CVE-2026-44476 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-44476 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-44476 and fix it if it is affected.

What it is: CVE-2026-44476 is a medium-severity authentication bypass vulnerability in doorkeeper-gem doorkeeper-openid_connect, published on 25 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-44476 exists.

Affected packages and fixed versions:
- doorkeeper-openid_connect (RubyGems): affected from 1.9.0; fixed in 1.10.0
- doorkeeper-openid_connect (RubyGems): affected from 1.9.0; fixed in 1.10.0

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-2026-44476/ (Markdown: https://insights.sbomify.com/CVE-2026-44476/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-44476
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-44476
- OSV: https://osv.dev/vulnerability/CVE-2026-44476

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-44476/
Summaries are generated and may contain mistakes; the official description above is the record.