DuendeSoftware foss up to 3.1.x HttpContext.GetClientAccessTokenAsync toctou

Summaryinfo

A vulnerability marked as problematic has been reported in DuendeSoftware foss up to 3.1.x. This affects the function HttpContext.GetClientAccessTokenAsync. Performing a manipulation results in toctou. This vulnerability is cataloged as CVE-2025-26620. It is possible to initiate the attack remotely. There is no exploit available. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as problematic, was found in DuendeSoftware foss up to 3.1.x. This affects the function HttpContext.GetClientAccessTokenAsync. The manipulation with an unknown input leads to a toctou vulnerability. CWE is classifying the issue as CWE-367. The product checks the state of a resource before using that resource, but the resource's state can change between the check and the use in a way that invalidates the results of the check. This can cause the product to perform invalid actions when the resource is in an unexpected state. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

Duende.AccessTokenManagement is a set of .NET libraries that manage OAuth and OpenId Connect access tokens. Duende.AccessTokenManagement contains a race condition when requesting access tokens using the client credentials flow. Concurrent requests to obtain an access token using differing protocol parameters can return access tokens obtained with the wrong scope, resource indicator, or other protocol parameters. Such usage is somewhat atypical, and only a small percentage of users are likely to be affected. Duende.AccessTokenManagement can request access tokens using the client credentials flow in several ways. In basic usage, the client credentials flow is configured once and the parameters do not vary. In more advanced situations, requests with varying protocol parameters may be made by calling specific overloads of these methods: `HttpContext.GetClientAccessTokenAsync()` and `IClientCredentialsTokenManagementService.GetAccessTokenAsync()`. There are overloads of both of these methods that accept a `TokenRequestParameters` object that customizes token request parameters. However, concurrent requests with varying `TokenRequestParameters` will result in the same token for all concurrent calls. Most users can simply update the NuGet package to the latest version. Customizations of the `IClientCredentialsTokenCache` that derive from the default implementation (`DistributedClientCredentialsTokenCache`) will require a small code change, as its constructor was changed to add a dependency on the `ITokenRequestSynchronization` service. The synchronization service will need to be injected into the derived class and passed to the base constructor. The impact of this vulnerability depends on how Duende.AccessTokenManagement is used and on the security architecture of the solution. Most users will not be vulnerable to this issue. More advanced users may run into this issue by calling the methods specified above with customized token request parameters. The impact of obtaining an access token with different than intended protocol parameters will vary depending on application logic, security architecture, and the authorization policy of the resource servers.

It is possible to read the advisory at github.com. This vulnerability is uniquely identified as CVE-2025-26620 since 02/12/2025. The exploitability is told to be difficult. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. Technical details of the vulnerability are known, but there is no available exploit.

Upgrading to version 3.2.0 eliminates this vulnerability.

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Productinfo

Vendor

• DuendeSoftware

Name

• foss

Version

• 3.0
• 3.1

Website

• Product: https://github.com/DuendeSoftware/foss/

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CPE 2.2info

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