GHSA-8fh9-c4jq-94h4 idunno.Bluesky, idunno.AtProto and idunno.AtProto.OAuthCallback Denial of Service Vulnerability
A denial of service vulnerability in a transitive dependency affects Bluesky and AtProto libraries, requiring an upgrade to resolve.
- Exploited in the wild
- Not known
- Login needed
- Not stated
- Attackable
- Over the internet
- Victim action needed
- Not stated
- Fix
- Available
What is GHSA-8fh9-c4jq-94h4?
GHSA-8fh9-c4jq-94h4 is a denial of service vulnerability in idunno.AtProto, published on 13 Mar 2026. It can be exploited over the network.
Official description
idunno.Bluesky, idunno.AtProto and idunno.AtProto.OAuthCallback Denial of Service Vulnerability
Impact
The Microsoft.Bcl.Memory package, a transitive dependency of idunno.AtProto and idunno.AtProto.OAuthCallback had a Denial of Service security vulnerability, CVE-2026-26127
Patches
v1.7.0 updates the dependencies on Duende.IdentityModel.OidcClient and Duende.IdentityModel.OidcClient.Extensions which, in turn, updates their dependency on Microsoft.Bcl.Memory to 10.0.4, resolving the vulnerability.
Workarounds
No workarounds exist for this vulnerability.
How to fix the issue
To update your dependencies on idunno.Bluesky, idunno.AtProto and idunno.AtProto.OAuthCallback,
Using the .NET CLI (Command Line Interface):
Open a terminal or command prompt in your project's directory.
To update a specific package to its latest version, use the following add package command:
If you are using
idunno.Blueskydotnet package update idunno.BlueskyIf you are using
idunno.AtProtoas a direct dependencydotnet package update idunno.AtProtoIf you are using
idunno.AtProto.OAuthCallbackas a direct dependencydotnet package update idunno.AtProto.OAuthCallback
Using the NuGet Package Manager Console in Visual Studio:
Open your project in Visual Studio.
Navigate to "Tools > NuGet Package Manager > Package Manager Console".
To update a specific package to its latest version, use the following Update-Package command:
If you are using
idunno.BlueskyUpdate-Package -Id idunno.BlueskyIf you are using
idunno.AtProtoas a direct dependencyUpdate-Package -Id idunno.AtProtoIf you are using
idunno.AtProto.OAuthCallbackas a direct dependencyUpdate-Package -Id idunno.AtProto.OAuthCallback
NuGet Package Manager UI in Visual Studio:
- Open your project in Visual Studio.
- Right-click on your project in Solution Explorer and select "Manage NuGet Packages…" or navigate to "Project > Manage NuGet Packages".
- In the NuGet Package Manager window, select the "Updates" tab. This tab lists packages with available updates from your configured package sources.
- Select the package(s) you wish to update. You can choose a specific version from the dropdown or update to the latest available version.
- Click the "Update" button.
References
Which versions are affected by GHSA-8fh9-c4jq-94h4?
6 open source packages ship an affected version, including idunno.AtProto, idunno.AtProto.OAuthCallback and idunno.Bluesky.
| Package | Affected | Fixed in |
|---|---|---|
idunno.AtProto NuGet | All versions | 1.7.0 |
idunno.AtProto NuGet | All versions | 1.7.0 |
idunno.AtProto.OAuthCallback NuGet | All versions | 1.7.0 |
idunno.AtProto.OAuthCallback NuGet | All versions | 1.7.0 |
idunno.Bluesky NuGet | All versions | 1.7.0 |
idunno.Bluesky NuGet | All versions | 1.7.0 |
How do I fix GHSA-8fh9-c4jq-94h4?
Upgrade idunno.AtProto to 1.7.0 or later.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is GHSA-8fh9-c4jq-94h4 being exploited?
There is no known exploitation of GHSA-8fh9-c4jq-94h4 in the wild and no public exploit code.