CVE-2026-118750 is a high-severity (CVSS 7.5) CWE-770 vulnerability in Microsoft.AspNetCore.WebUtilities. A fix is available for Microsoft.AspNetCore.WebUtilities — see the affected versions and patch details below.
Microsoft Security Advisory CVE-2026-118750 - ASP.NET Core 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 CVE-2026-118750.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
Microsoft.AspNetCore.WebUtilitiesReal-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
Executive summary
Microsoft is releasing this security advisory to provide information about a vulnerability in ASP.NET Core. This advisory provides guidance on updating affected applications and components.
FileBufferingReadStream buffer allocation can allow unauthenticated multipart-form requests to exhaust memory.
Announcement
Announcement for this issue can be found at https://github.com/dotnet/announcements/issues/512
CVSS Details
- Version: 3.1
- Severity: High
- Score: 7.5 (base score)
- 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 - Weakness: CWE-770
Affected Platforms
- Platforms: Any supported OS
- Architectures: All
<a name="affected-packages"></a>Affected Packages
The table lists the affected package range and the fixed NuGet version.
ASP.NET Core 2.3 - standalone packages
| Package | Affected version | Patched version |
|---|---|---|
| Microsoft.AspNetCore.WebUtilities | >= 2.3.0, <= 2.3.13 | 2.3.14 |
Advisory FAQ
<a name="how-affected"></a>How do I know if I am affected?
Check the application's Microsoft.AspNetCore.WebUtilities package reference against the affected range above, including transitive dependencies brought in by Microsoft.AspNetCore.Http. Use dotnet list <PROJECT> package --include-transitive to inspect resolved dependencies.
<a name="how-fix"></a>How do I fix the issue?
Update each applicable package reference to its patched version listed above, then rebuild and redeploy the application. Updating only the installed runtime does not update an application's standalone package references.
Applications referencing Microsoft.AspNetCore.Http must resolve Microsoft.AspNetCore.WebUtilities to version 2.3.14 or later. Add or update a direct WebUtilities reference if necessary to override an older transitive dependency.
Other Information
Reporting Security Issues
If you have found a potential security issue in a supported version of .NET, please report it 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
You can ask questions about this issue 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. You can ask questions 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
Acknowledgements
- NavSec4
Revisions
V1.0 (November 10, 2026): Advisory published.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| .NETNuGet | Microsoft.AspNetCore.WebUtilities | ≥ 2.3.0&&< 2.3.14 | 2.3.14dotnet add package Microsoft.AspNetCore.WebUtilities --version 2.3.14 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for Microsoft.AspNetCore.WebUtilities, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update Microsoft.AspNetCore.WebUtilities to 2.3.14 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-118750 is resolved across your whole dependency graph.
Workarounds
Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.
Frequently Asked Questions
Is CVE-2026-118750 in your dependencies?
Find it across NuGet, including transitive dependencies.