---
id: CVE-2026-49272
aliases:
  - GHSA-3jp2-3mrg-2vxc
title: >-
  OAuthLib: Bearer token can be retrieved as long as client knows a valid client
  ID for device workflow
summary: >-
  OAuthLib: Bearer token can be retrieved as long as client knows a valid client
  ID for device workflow
severity: high
cvss: 8.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:H/A:N'
vendor: oauthlib
product: oauthlib
ecosystem: pip
affected:
  - 'oauthlib >= 3.3.0, < 4.0.0'
patched:
  - oauthlib 4.0.0
published: '2026-10-27'
updated: '2026-10-27'
sourceUpdated: '2026-10-27T13:45:03.096035248Z'
source: OSV
sourceUrl: 'https://osv.dev/vulnerability/GHSA-3jp2-3mrg-2vxc'
references:
  - url: >-
      https://github.com/oauthlib/oauthlib/security/advisories/GHSA-3jp2-3mrg-2vxc
  - url: 'https://github.com/oauthlib/oauthlib'
  - url: 'https://github.com/oauthlib/oauthlib/releases/tag/v4.0.0'
  - url: 'https://github.com/advisories/GHSA-3jp2-3mrg-2vxc'
tags:
  - osv
  - pip
  - ghsa
cwe:
  - CWE-287
ingestedAt: '2026-10-27T16:11:58.757Z'
---

## Overview

### Summary
A call to the token endpoint with a grant type of `"urn:ietf:params:oauth:grant-type:device_code"` and a bogus `device_code` is able to get a bearer token as long as they know a valid client ID enabled for the device workflow.

### Details

[Section 3.4 of the RFC 8628 spec](https://datatracker.ietf.org/doc/html/rfc8628#section-3.4) says that the token endpoint should take in `device_code` as a required parameter.`DeviceCodeGrant.validate_token_request` does not perform any validation of `device_code`. `DeviceCodeGrant.validate_token_request` should be validating that `device_code` was passed in as a parameter and that it is valid, similar to how `AuthorizationCodeGrant.validate_token_request` does the checks [here](https://github.com/oauthlib/oauthlib/blob/a015b446622f2b925517501fe484c10eff7a83c0/oauthlib/oauth2/rfc6749/grant_types/authorization_code.py#L446) and [here](https://github.com/oauthlib/oauthlib/blob/a015b446622f2b925517501fe484c10eff7a83c0/oauthlib/oauth2/rfc6749/grant_types/authorization_code.py#L483).

I would like to propose a new method be added to `RequestValidator` called `validate_device_code` that is similar to the `validate_code` method and is called inside of `DeviceCodeGrant.validate_token_request`.

### PoC
Create an implementation of `RequestValidation.authenticate_client` that returns `True` if the client's `client_type` is `"public"`. You would find yourself in this scenario because there's another issue with `DeviceCodeGrant.validate_token_request` where it doesn't properly handle public clients (see https://github.com/oauthlib/oauthlib/issues/919).

Create a client that has a `client_type` of `"public"` and set it's `grant_type` to `"urn:ietf:params:oauth:grant-type:device_code"`.

With this implementation of `RequestValidation.authenticate_client` done, use that validator for your token endpoint. Call the token endpoint with a body of 
```
{
  "client_id": <ID of the public client you made>,
  "grant_type": "urn:ietf:params:oauth:grant-type:device_code",
  "device_code": <anything you want since it's not validated>
}
```

You now have a bearer token for the client without a valid `device_code`.


### Impact
Anyone using the RFC 8628 device workflow in oauthlib that doesn't realize the `device_code` parameter is not being validated.

## Affected packages

- `oauthlib >= 3.3.0, < 4.0.0`

## Remediation

Upgrade to a patched release:

- `oauthlib 4.0.0`