Auth bypass in Duendesoftware Identityserver

CVE-2024-49755

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.

Vulnerability class: Broken Authentication

Published · last modified .

CVSS v3 metric

CVSS v3 base score 3.1 (Low). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:N/A:N.

EPSS exploit prediction

EPSS: 0.003 (23.5th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 24th percentile — 23.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2024-49755: held from 0.003 to 0.003.

EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: 0.000

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2024-49755?
CVE-2024-49755 is a low-severity vulnerability in Duendesoftware Identityserver, classified under Improper Authentication. CVSS score: 3.1/10. Published 2024-10-28.
How severe is CVE-2024-49755?
Low severity. CVSS v3 base score is 3.1 out of 10.