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.NET
.NET NuGet
Not in CISA KEV
HIGH severity

GHSA-8fh9-c4jq-94h4 — idunno.AtProto

HIGH

GHSA-8fh9-c4jq-94h4 is a high-severity (CVSS 7.5) vulnerability in idunno.AtProto. A fix is available for idunno.AtProto — see the affected versions and patch details below.

idunno.Bluesky, idunno.AtProto and idunno.AtProto.OAuthCallback Denial of Service Vulnerability

Published
Mar 13, 2026
Updated
Mar 13, 2026
Affected
3 pkgs
Patched
3 / 3
Exploits
None indexed
Exploitation data as of Mar 13, 2026 · OSV.dev, FIRST.org (EPSS)

Real-World Exposure

3 pkgs affected
.NETidunno.AtProto.NETidunno.AtProto.OAuthCallback.NETidunno.Bluesky

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

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.Bluesky dotnet package update idunno.Bluesky

    • If you are using idunno.AtProto as a direct dependency dotnet package update idunno.AtProto

    • If you are using idunno.AtProto.OAuthCallback as a direct dependency dotnet 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.Bluesky Update-Package -Id idunno.Bluesky

    • If you are using idunno.AtProto as a direct dependency Update-Package -Id idunno.AtProto

    • If you are using idunno.AtProto.OAuthCallback as a direct dependency Update-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

Affected Packages

3 total 3 fixed
EcosystemPackageVulnerable rangeFix
.NETNuGetidunno.AtProtoall versions1.7.0dotnet add package idunno.AtProto --version 1.7.0
.NETNuGetidunno.AtProto.OAuthCallbackall versions1.7.0dotnet add package idunno.AtProto.OAuthCallback --version 1.7.0
.NETNuGetidunno.Blueskyall versions1.7.0dotnet add package idunno.Bluesky --version 1.7.0

Detection & mitigation playbook

Open-source dependency

  1. Detect

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

  2. Fix

    Update idunno.AtProto to 1.7.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-8fh9-c4jq-94h4 is resolved across your whole dependency graph.

  3. 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.

  4. How O3 protects you

    O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-8fh9-c4jq-94h4 can be triaged on real exposure rather than presence alone.

Tailored to GHSA-8fh9-c4jq-94h4. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

# 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](https://github.com/dotnet/announcements/issues/384) ## 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
O3 Security · Impact-Aware SCA

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GHSA-8fh9-c4jq-94h4: DoS (High 7.5) | O3 Security