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CVE-2025-26620— Duende.AccessTokenManagement race condition when concurrently retrieving customized Client Credentials Access Tokens

Quick assessment

Affected
DuendeSoftware foss
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Duende.AccessTokenManagement是Duende开源的一个库。用于管理 OAuth 和 OpenId Connect 访问令牌。 Duende.AccessTokenManagement存在安全漏洞,该漏洞源于在使用客户端凭证流时未正确处理并发请求。攻击者利用该漏洞可以获取错误的访问令牌。

AI Predicted 5.3 Difficulty: Moderate EPSS 0.39% · P31

Possible ATT&CK Techniques 1 AI

T1078.004 · Cloud Accounts
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I. Basic Information for CVE-2025-26620

Vulnerability Information

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Vulnerability Title
Duende.AccessTokenManagement race condition when concurrently retrieving customized Client Credentials Access Tokens
Source: CVE Program / CVE List V5
Vulnerability Description
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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N
Source: CVE Program / CVE List V5
Vulnerability Type
检查时间与使用时间(TOCTOU)的竞争条件
Source: CVE Program / CVE List V5
Vulnerability Title
Duende.AccessTokenManagement 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Duende.AccessTokenManagement是Duende开源的一个库。用于管理 OAuth 和 OpenId Connect 访问令牌。 Duende.AccessTokenManagement存在安全漏洞,该漏洞源于在使用客户端凭证流时未正确处理并发请求。攻击者利用该漏洞可以获取错误的访问令牌。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
DuendeSoftware foss < 3.2.0 -

II. Public POCs for CVE-2025-26620

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III. Intelligence Information for CVE-2025-26620

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Patches & Fixes for CVE-2025-26620 (1)

Vendor Advisories for CVE-2025-26620 (1)

IV. Related Vulnerabilities

V. Comments for CVE-2025-26620

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