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Use client_secret_basic by default, use client_secret_post if supported #1199

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Merged
julien-nc merged 2 commits into from
Sep 22, 2025
Merged

Use client_secret_basic by default, use client_secret_post if supported #1199

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03b52d5
fix(tokenEndpointAuth): use client_secret_basic by default, use clien…
julien-nc Sep 11, 2025
a647192
fix(tokenEndpointAuth): allow setting the default token endpoint auth…
julien-nc Sep 11, 2025
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16 changes: 16 additions & 0 deletions README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -55,6 +55,22 @@ for private or internal applications without requiring user consent or interacti
Documentation for all supported prompt values is available here:
[Oauth2 passport server prompts-supported](https://gitlab.com/elyerr/oauth2-passport-server/-/wikis/home/prompts-supported)

## `user_oidc.default_token_endpoint_auth_method`

The OIDC specifications are clear on this. It is stated in https://openid.net/specs/openid-connect-discovery-1_0.html
that if `token_endpoint_auth_methods_supported` is not set in the provider discovery endpoint payload,
`client_secret_basic` should be used as default authentication method.

But it has been reported that, with Authelia for example, only `client_secret_post` might be allowed while `token_endpoint_auth_methods_supported`
is not set in the discovery. In such case, you can set the default token endpoint authentication method with:

```php
'user_oidc' => [
'default_token_endpoint_auth_method' => 'client_secret_post'
]
```


---

### User IDs
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18 changes: 12 additions & 6 deletions lib/Controller/LoginController.php
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Expand Up @@ -385,18 +385,24 @@ public function code(string $state = '', string $code = '', string $scope = '',
}

$headers = [];
$tokenEndpointAuthMethod = 'client_secret_post';
// Use Basic only if client_secret_post is not available as supported by the endpoint
// follow what is described in https://openid.net/specs/openid-connect-discovery-1_0.html
// about token_endpoint_auth_methods_supported: "If omitted, the default is client_secret_basic"
// Use client_secret_post if supported
// We still allow changing the default auth method in config.php
$tokenEndpointAuthMethod = $oidcSystemConfig['default_token_endpoint_auth_method'] ?? 'client_secret_basic';
// deal with invalid values
if (!in_array($tokenEndpointAuthMethod, ['client_secret_basic', 'client_secret_post'], true)) {
$tokenEndpointAuthMethod = 'client_secret_basic';
}
if (
array_key_exists('token_endpoint_auth_methods_supported', $discovery)
&& is_array($discovery['token_endpoint_auth_methods_supported'])
&& in_array('client_secret_basic', $discovery['token_endpoint_auth_methods_supported'])
&& !in_array('client_secret_post', $discovery['token_endpoint_auth_methods_supported'])
&& in_array('client_secret_post', $discovery['token_endpoint_auth_methods_supported'], true)
) {
$tokenEndpointAuthMethod = 'client_secret_basic';
$tokenEndpointAuthMethod = 'client_secret_post';
}

if ($tokenEndpointAuthMethod == 'client_secret_basic') {
if ($tokenEndpointAuthMethod === 'client_secret_basic') {
$headers = [
'Authorization' => 'Basic ' . base64_encode($provider->getClientId() . ':' . $providerClientSecret),
'Content-Type' => 'application/x-www-form-urlencoded',
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