VulnerabilityDeferred

CVE-2024-39694

It is possible for an attacker to craft malicious Urls that certain functions in IdentityServer will incorrectly treat as local and trusted.

MEDIUM 4.7EPSS 0.53%

Does this matter?

Lower severity and a low EPSS score (0.53%). Track it; it rarely justifies an emergency change on its own.

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.

CVSS 3.1: 4.7 MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:N/A:N
EPSS: 0.53% probability · 45th percentile
Public exploits: None in Exploit-DB
CISA KEV: Not listed
Weakness: CWE-601
Source: security-advisories@github.com

EPSS trend

EPSS 0.5% since 27 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.

References

Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.