GHSA-73j8-2gch-69rq — Microsoft.Bcl.Memory
HIGHGHSA-73j8-2gch-69rq is a high-severity (CVSS 7.5) Out-of-bounds Read vulnerability in Microsoft.Bcl.Memory. A fix is available for Microsoft.Bcl.Memory — see the affected versions and patch details below.
.NET Denial of Service Vulnerability
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for GHSA-73j8-2gch-69rq.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
GHSA-73j8-2gch-69rq plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 378,567 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
Microsoft.Bcl.Memory.NETMicrosoft.NetCore.App.Runtime.linux-arm.NETMicrosoft.NetCore.App.Runtime.linux-arm64.NETMicrosoft.NetCore.App.Runtime.linux-musl-arm.NETMicrosoft.NetCore.App.Runtime.linux-musl-arm64.NETMicrosoft.NetCore.App.Runtime.linux-musl-x64.NETMicrosoft.NetCore.App.Runtime.linux-x64.NETMicrosoft.NetCore.App.Runtime.osx-arm64+18 moreReal-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
Microsoft Security Advisory CVE-2026-26127 – .NET Denial of Service Vulnerability
Executive summary
Microsoft is releasing this security advisory to provide information about a vulnerability in .NET 9.0 and .NET 10.0. This advisory also provides guidance on what developers can do to update their applications to remove this vulnerability.
A denial of service vulnerability exists in .NET and Microsoft.Bcl.Memory due to an out-of-bounds read when decoding malformed Base64Url input.
Announcement
Announcement for this issue can be found at https://github.com/dotnet/announcements/issues/384
CVSS Details
- Version: 3.1
- Score: 7.5
- Vector:
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C - Severity: High
- Weakness: CWE-129 (Improper Validation of Array Index); CWE-125 (Out-of-bounds Read)
Affected Platforms
- Platforms: All
- Architectures: All
Affected Products
<a name=".NET 9"></a>.NET 9
| Package name | Affected version | Patched version |
|---|---|---|
| Microsoft.NetCore.App.Runtime.linux-arm | >= 9.0.0, <= 9.0.13 | 9.0.14 |
| Microsoft.NetCore.App.Runtime.linux-arm64 | >= 9.0.0, <= 9.0.13 | 9.0.14 |
| Microsoft.NetCore.App.Runtime.linux-musl-arm | >= 9.0.0, <= 9.0.13 | 9.0.14 |
| Microsoft.NetCore.App.Runtime.linux-musl-arm64 | >= 9.0.0, <= 9.0.13 | 9.0.14 |
| Microsoft.NetCore.App.Runtime.linux-musl-x64 | >= 9.0.0, <= 9.0.13 | 9.0.14 |
| Microsoft.NetCore.App.Runtime.linux-x64 | >= 9.0.0, <= 9.0.13 | 9.0.14 |
| Microsoft.NetCore.App.Runtime.osx-arm64 | >= 9.0.0, <= 9.0.13 | 9.0.14 |
| Microsoft.NetCore.App.Runtime.osx-x64 | >= 9.0.0, <= 9.0.13 | 9.0.14 |
| Microsoft.NetCore.App.Runtime.win-arm | >= 9.0.0, <= 9.0.13 | 9.0.14 |
| Microsoft.NetCore.App.Runtime.win-arm64 | >= 9.0.0, <= 9.0.13 | 9.0.14 |
| Microsoft.NetCore.App.Runtime.win-x64 | >= 9.0.0, <= 9.0.13 | 9.0.14 |
| Microsoft.NetCore.App.Runtime.win-x86 | >= 9.0.0, <= 9.0.13 | 9.0.14 |
<a name=".NET 10"></a>.NET 10
| Package name | Affected version | Patched version |
|---|---|---|
| Microsoft.NetCore.App.Runtime.linux-arm | >= 10.0.0, <= 10.0.3 | 10.0.4 |
| Microsoft.NetCore.App.Runtime.linux-arm64 | >= 10.0.0, <= 10.0.3 | 10.0.4 |
| Microsoft.NetCore.App.Runtime.linux-musl-arm | >= 10.0.0, <= 10.0.3 | 10.0.4 |
| Microsoft.NetCore.App.Runtime.linux-musl-arm64 | >= 10.0.0, <= 10.0.3 | 10.0.4 |
| Microsoft.NetCore.App.Runtime.linux-musl-x64 | >= 10.0.0, <= 10.0.3 | 10.0.4 |
| Microsoft.NetCore.App.Runtime.linux-x64 | >= 10.0.0, <= 10.0.3 | 10.0.4 |
| Microsoft.NetCore.App.Runtime.osx-arm64 | >= 10.0.0, <= 10.0.3 | 10.0.4 |
| Microsoft.NetCore.App.Runtime.osx-x64 | >= 10.0.0, <= 10.0.3 | 10.0.4 |
| Microsoft.NetCore.App.Runtime.win-arm | >= 10.0.0, <= 10.0.3 | 10.0.4 |
| Microsoft.NetCore.App.Runtime.win-arm64 | >= 10.0.0, <= 10.0.3 | 10.0.4 |
| Microsoft.NetCore.App.Runtime.win-x64 | >= 10.0.0, <= 10.0.3 | 10.0.4 |
| Microsoft.NetCore.App.Runtime.win-x86 | >= 10.0.0, <= 10.0.3 | 10.0.4 |
<a name="Microsoft.Bcl.Memory 9.0.14"></a>Microsoft.Bcl.Memory 9.0.14
| Package name | Affected version | Patched version |
|---|---|---|
| Microsoft.Bcl.Memory | >= 9.0.0, <= 9.0.13 | 9.0.14 |
<a name="Microsoft.Bcl.Memory 10.0.4"></a>Microsoft.Bcl.Memory 10.0.4
| Package name | Affected version | Patched version |
|---|---|---|
| Microsoft.Bcl.Memory | >= 10.0.0, <= 10.0.3 | 10.0.4 |
<a name="how-fix"></a>How to fix the issue
To update the Microsoft.Bcl.Memory NuGet package, apply one of the following methods:
NuGet Package Manager UI in Visual Studio:
- Open the project in Visual Studio.
- Right-click on the 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 the configured package sources.
- Select the package(s) to update. A specific version can be chosen from the dropdown, or the latest available version can be selected.
- Click the "Update" button.
Using the NuGet Package Manager Console in Visual Studio:
- Open the project in Visual Studio.
- Navigate to "Tools > NuGet Package Manager > Package Manager Console".
- To update a specific package to its latest version, run the following Update-Package command:
Update-Package -Id Microsoft.Bcl.Memory
Using the .NET CLI (Command Line Interface):
- Open a terminal or command prompt in the project's directory.
- To update a specific package to its latest version, run the following command:
dotnet package update Microsoft.Bcl.Memory
Once the NuGet package reference has been updated, the application must be recompiled and redeployed. Additionally, it is recommended to update the runtime and/or SDKs, but unless the application targets .NET 9 or higher, updating the runtime and/or SDK is not a required step to patch this vulnerability.
Other Information
Reporting Security Issues
If a potential security issue has been found in a supported version of .NET, it should be reported to the Microsoft Security Response Center (MSRC) via the MSRC Researcher Portal. Further information can be found in the MSRC Report an Issue FAQ.
Security reports made through MSRC may qualify for the Microsoft .NET Bounty. Details of the Microsoft .NET Bounty Program including terms and conditions are at https://aka.ms/corebounty.
Support
Questions about this issue can be asked on GitHub in the .NET GitHub organization. The main repos are located at https://github.com/dotnet/runtime. The Announcements repo (https://github.com/dotnet/Announcements) will contain this bulletin as an issue and will include a link to a discussion issue. Questions can be asked in the linked discussion issue.
Disclaimer
The information provided in this advisory is provided "as is" without warranty of any kind. Microsoft disclaims all warranties, either express or implied, including the warranties of merchantability and fitness for a particular purpose. In no event shall Microsoft Corporation or its suppliers be liable for any damages whatsoever including direct, indirect, incidental, consequential, loss of business profits or special damages, even if Microsoft Corporation or its suppliers have been advised of the possibility of such damages. Some states do not allow the exclusion or limitation of liability for consequential or incidental damages so the foregoing limitation may not apply.
External Links
Revisions
V1.0 (March 10, 2026): Advisory published.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| .NETNuGet | Microsoft.Bcl.Memory | ≥ 9.0.0&&< 9.0.14 | 9.0.14dotnet add package Microsoft.Bcl.Memory --version 9.0.14 |
| .NETNuGet | Microsoft.NetCore.App.Runtime.linux-arm | ≥ 9.0.0&&< 9.0.14 | 9.0.14dotnet add package Microsoft.NetCore.App.Runtime.linux-arm --version 9.0.14 |
| .NETNuGet | Microsoft.NetCore.App.Runtime.linux-arm64 | ≥ 9.0.0&&< 9.0.14 | 9.0.14dotnet add package Microsoft.NetCore.App.Runtime.linux-arm64 --version 9.0.14 |
| .NETNuGet | Microsoft.NetCore.App.Runtime.linux-musl-arm | ≥ 9.0.0&&< 9.0.14 | 9.0.14dotnet add package Microsoft.NetCore.App.Runtime.linux-musl-arm --version 9.0.14 |
| .NETNuGet | Microsoft.NetCore.App.Runtime.linux-musl-arm64 | ≥ 9.0.0&&< 9.0.14 | 9.0.14dotnet add package Microsoft.NetCore.App.Runtime.linux-musl-arm64 --version 9.0.14 |
| .NETNuGet | Microsoft.NetCore.App.Runtime.linux-musl-x64 | ≥ 9.0.0&&< 9.0.14 | 9.0.14dotnet add package Microsoft.NetCore.App.Runtime.linux-musl-x64 --version 9.0.14 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for Microsoft.Bcl.Memory, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update Microsoft.Bcl.Memory to 9.0.14 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-73j8-2gch-69rq is resolved across your whole dependency graph.
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.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-73j8-2gch-69rq can be triaged on real exposure rather than presence alone.
Tailored to GHSA-73j8-2gch-69rq. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat Enterprise Linux 10 | dotnet9.0-0:9.0.115-1.el10_1 | RHSA-2026:4450 |
| Red Hat Enterprise Linux 10 | dotnet10.0-0:10.0.104-1.el10_1 | RHSA-2026:4453 |
| Red Hat Enterprise Linux 10.0 Extended Update Support | dotnet9.0-0:9.0.115-1.el10_0 | RHSA-2026:10083 |
| Red Hat Enterprise Linux 8 | dotnet9.0-0:9.0.115-1.el8_10 | RHSA-2026:4443 |
| Red Hat Enterprise Linux 8 | dotnet10.0-0:10.0.104-1.el8_10 | RHSA-2026:4458 |
| Red Hat Enterprise Linux 9 | dotnet10.0-0:10.0.104-1.el9_7 | RHSA-2026:4445 |
| Red Hat Enterprise Linux 9 | dotnet9.0-0:9.0.115-1.el9_7 | RHSA-2026:4456 |
| Red Hat Enterprise Linux 9.6 Extended Update Support | dotnet9.0-0:9.0.115-1.el9_6 | RHSA-2026:10085 |
Frequently Asked Questions
Is GHSA-73j8-2gch-69rq in your dependencies?
O3 Security finds GHSA-73j8-2gch-69rq across NuGet dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.