CVE-2024-39694 is a medium-severity (CVSS 4.7) Open Redirect vulnerability in Duende.IdentityServer. O3 Security confirms whether CVE-2024-39694 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Duende IdentityServer Open Redirect vulnerability
Real-World Exposure
Duende.IdentityServer.NETDuende.IdentityServer.NETDuende.IdentityServer.NETDuende.IdentityServer.NETDuende.IdentityServer.NETIdentityServer4Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects NuGet packages — download data is not available via public APIs for these ecosystems.
Description
Duende IdentityServer is an OpenID Connect and OAuth 2.x framework for ASP.NET Core. It is possible for an attacker to craft malicious Urls that certain functions in IdentityServer will incorrectly treat as local and trusted. If such a Url is returned as a redirect, some browsers will follow it to a third-party, untrusted site. Note: by itself, this vulnerability does not allow an attacker to obtain user credentials, authorization codes, access tokens, refresh tokens, or identity tokens. An attacker could however exploit this vulnerability as part of a phishing attack designed to steal user credentials. This vulnerability is fixed in 7.0.6, 6.3.10, 6.2.5, 6.1.8, and 6.0.5. Duende.IdentityServer 5.1 and earlier and all versions of IdentityServer4 are no longer supported and will not be receiving updates. If upgrading is not possible, use IUrlHelper.IsLocalUrl from ASP.NET Core to validate return Urls in user interface code in the IdentityServer host.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| .NETNuGet | Duende.IdentityServer | ≥ 7.0.0-preview.1&&< 7.0.6 | 7.0.6 |
| .NETNuGet | Duende.IdentityServer | ≥ 6.3.0-preview.1&&< 6.3.10 | 6.3.10 |
| .NETNuGet | Duende.IdentityServer | ≥ 6.2.0-preview.1&&< 6.2.5 | 6.2.5 |
| .NETNuGet | Duende.IdentityServer | ≥ 6.1.0-preview.1&&< 6.1.8 | 6.1.8 |
| .NETNuGet | Duende.IdentityServer | ≥ 6.0.0-preview.1&&< 6.0.5 | 6.0.5 |
| .NETNuGet | IdentityServer4 | all versions | No fix |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for Duende.IdentityServer. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update Duende.IdentityServer to 7.0.6 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2024-39694 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2024-39694 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2024-39694. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2024-39694 in your dependencies?
O3 detects CVE-2024-39694 across NuGet dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.