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.NET
.NET NuGet
Not in CISA KEV
MEDIUM severity

IdentityServer Open Redirect vulnerabilityGHSA-55p7-v223-x366

MEDIUM

GHSA-55p7-v223-x366 is a medium-severity (CVSS 4.7) vulnerability in IdentityServer4. The records list no fixed version yet; check the vendor advisory below and apply the mitigations in the meantime.

Published
Updated
Affected
1 pkg
Patched
None yet
Exploits
None indexed
Exploitation data as of Nov 30, 2024 · OSV.dev, FIRST.org (EPSS)

Real-World Exposure

1 pkg affected
.NETIdentityServer4

Real-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

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.

Affected Methods

  • In the DefaultIdentityServerInteractionService, the GetAuthorizationContextAsync method may return non-null and the IsValidReturnUrl method 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.ParseAsync and OidcReturnUrlParser.ParseAsync methods may incorrectly return non-null, and the ReturnUrlParser.IsValidReturnUrl and OidcReturnUrlParser.IsValidReturnUrl methods may incorrectly return true for malicious Urls.

Patches

IdentityServer4 is no longer supported and will not be receiving updates. Please consider updating to Duende.IdentityServer.

Affected Packages

1 total
EcosystemPackageVulnerable rangeFix
.NETNuGetIdentityServer4all versionsNo fix

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for IdentityServer4, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Remediation status

    The records we use list no patched version of IdentityServer4 for GHSA-55p7-v223-x366. Check the maintainer's advisory, and where your build allows, override or pin the dependency away from the vulnerable range.

  3. Mitigate without a patch

    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.

Frequently Asked Questions

### 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. ### Affected Methods - In the `DefaultIdentityServerInteractionService`, the `GetAuthorizationContextAsync` method may return non-null and the `IsValidReturnUrl` method 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 t
O3 Security · Impact-Aware SCA

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IdentityServer Open Redirect vulnerability (Medium 4.7)