Summary
IdentityServer Open Redirect vulnerability
Affected Methods
In the
DefaultIdentityServerInteractionService, theGetAuthorizationContextAsyncmethod may return non-null and theIsValidReturnUrlmethod may return true for malicious Urls, indicating incorrectly that they can be safely redirected to.UI code calling these two methods is the most commonly used code path that will expose the vulnerability. The default UI templates rely on this behavior in the Login, Challenge, and Consent pages. Customized user interface code might also rely on this behavior. The following uncommonly used APIs are also vulnerable:
The
ServerUrlExtensions.GetIdentityServerRelativeUrl,ReturnUrlParser.ParseAsyncandOidcReturnUrlParser.ParseAsyncmethods may incorrectly return non-null, and theReturnUrlParser.IsValidReturnUrlandOidcReturnUrlParser.IsValidReturnUrlmethods may incorrectly return true for malicious Urls.
Impact
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.
Untrusted input controls a URL used for redirection, which can forward users to attacker-controlled sites. Typical impact: phishing and credential harvesting via a trusted domain.
GHSA-55P7-V223-X366 has a CVSS score of 4.7 (Medium). The vector is network-reachable, no privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. No fixed version is listed yet, so configuration controls and monitoring matter more in the interim.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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IdentityServer4 is no longer supported and will not be receiving updates. Please consider updating to Duende.IdentityServer.
Frequently Asked Questions
- What is GHSA-55P7-V223-X366? GHSA-55P7-V223-X366 is a medium-severity open redirect vulnerability in IdentityServer4 (nuget), affecting versions <= 4.1.2. No fixed version is listed yet. Untrusted input controls a URL used for redirection, which can forward users to attacker-controlled sites.
- How severe is GHSA-55P7-V223-X366? GHSA-55P7-V223-X366 has a CVSS score of 4.7 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of IdentityServer4 are affected by GHSA-55P7-V223-X366? IdentityServer4 (nuget) versions <= 4.1.2 is affected.
- Is there a fix for GHSA-55P7-V223-X366? No fixed version is listed for GHSA-55P7-V223-X366 yet. Monitor the advisory for updates and apply mitigations in the interim.
- Is GHSA-55P7-V223-X366 exploitable, and should I be worried? Whether GHSA-55P7-V223-X366 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether GHSA-55P7-V223-X366 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix GHSA-55P7-V223-X366? No fixed version is listed yet. In the interim: Validate redirect destinations against an allowlist of permitted URLs or paths. Reject destinations that include an unexpected authority component.