# Duende.AccessTokenManagement race condition when concurrently retrieving customized Client Credentials Access Tokens

Advisory record · `GHSA-qxj7-2x7w-3mpp`

- **Identifiers:** `GHSA-qxj7-2x7w-3mpp` · `CVE-2025-26620`
- **State:** Confirmed
- **Severity:** CVSS 6.3 Medium
- **Critical:** No
- **Weakness (CWE):** [CWE-367](https://cwe.mitre.org/data/definitions/367.html)
- **Tags:** [Race condition](https://agentprime.io/advisories/tag/race-condition.md)
- **Published:** 19 Feb 2025
- **Updated:** 19 Feb 2025
- **Reviewed by a person:** No

Published by the GitHub Advisory Database at 19 Feb 2025, 17:47 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Affected packages

- `Duende.AccessTokenManagement` (NuGet): affected `<3.2.0`; fixed in `3.2.0`

## Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

> Duende.AccessTokenManagement versions before 3.2.0 contain a race condition in client credentials token retrieval. When concurrent calls use different TokenRequestParameters, they can receive a token issued with another call's scope, resource indicator, or other protocol parameters. The attacker-side conditions are not fully described, and the impact depends on the application's authorization setup. Upgrade to version 3.2.0 or later.

Written 9 Nov 2026.

## Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

## Severity and exploitation

- 6.3 Medium, CVSS 4.0: `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`, from CNA (GitHub_M)

- **CISA KEV:** Not listed.
- **EPSS:** 0.0039, the 33rd percentile, on 12 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

- 31 Oct 2026, 15:22 UTC: First seen by agentprime
- 31 Oct 2026, 15:22 UTC: [Confirmed by OSV](https://osv.dev/vulnerability/GHSA-qxj7-2x7w-3mpp)

## Sources

- [GitHub Advisory Database: GHSA-qxj7-2x7w-3mpp](https://github.com/advisories/GHSA-qxj7-2x7w-3mpp)
- [OSV: GHSA-qxj7-2x7w-3mpp](https://osv.dev/vulnerability/GHSA-qxj7-2x7w-3mpp)
- <https://github.com/DuendeSoftware/foss/security/advisories/GHSA-qxj7-2x7w-3mpp>
- <https://nvd.nist.gov/vuln/detail/CVE-2025-26620>
- <https://github.com/DuendeSoftware/foss/commit/a33332ddec0ebf3c048ba85427e3c77d47c68dac>
- <https://github.com/DuendeSoftware/foss>

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.

## Check whether this affects you

A Match means an installed version is in the affected range above. Most don’t affect the app; agentprime hasn’t analysed this one yet.

- With the agentprime MCP server (<https://api.agentprime.io/mcp>), ask your agent to check the project: `check_lockfile` sends a lockfile, `check_packages` a list of installed packages, and both return the Matches and the upgrades that clear them. `get_advisory` returns this record. Setup: <https://agentprime.io/mcp.md>
- In a browser: <https://agentprime.io/check/> reads your lockfile in the browser, never uploading it.
- Whether it touches your code, with file and line: the Claude Code plugin, <https://agentprime.io/plugin.md>
- As JSON: <https://api.agentprime.io/v1/advisories/GHSA-qxj7-2x7w-3mpp>, or `POST https://api.agentprime.io/v1/match` with your packages (<https://agentprime.io/api.md>)

---

The web page: <https://agentprime.io/advisories/GHSA-qxj7-2x7w-3mpp/>. Everything for agents: <https://agentprime.io/llms.txt>.