ASP.NET Core Tampering Vulnerability
Published October 13, 2026Updated October 13, 2026
Source data
Overview
Inconsistent interpretation of http requests ('http request/response smuggling') in ASP.NET Core allows an unauthorized attacker to perform tampering over a network.
Impact & technical details
Tampering
How could an attacker exploit this vulnerability? An unauthenticated attacker could send specially crafted HTTP/1.1 requests through a reverse proxy to an affected server. Successful exploitation could desynchronize request handling between the proxy and the server, allowing the attacker to inject an unintended request. User interaction is not required.
- CVSS base score
- 9.4 / 10
- CVSS vector
- CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L/E:U/RL:O/RC:C
Highest base score supplied by MSRC for this record; the vector belongs to that score. Ratings can vary by product. Microsoft Important is displayed as High; Moderate is displayed as Medium.
Affected products
- ASP.NET Core 10.0
- ASP.NET Core 11.0
- ASP.NET Core 8.0
- ASP.NET Core 9.0
- Microsoft Visual Studio 2022 version 17.14
- Microsoft Visual Studio 2026 version 18.10
Source guidance
Remediation
- Release Notes
At least one Microsoft vendor-fix reference is available. Check each affected product for its applicable update, prerequisites, and supported version.
GTP recommendation · Rule-based guidance
Recommended next step
Review affected Microsoft products and apply the applicable security updates through your organization's normal patch-management process. Confirm availability and prerequisites in the Microsoft advisory.
Authoritative sources & updates
Findings and update information come from the linked publishers. GTP compiles the public record and provides the recommendation above. CVSS ratings shown here come from Microsoft. NVD references provide additional public context.
- Microsoft Security Response Center (opens in a new tab)
- Microsoft security update · Release Notes (opens in a new tab)
- Microsoft remediation guidance (opens in a new tab)
- Microsoft security update · Release Notes (opens in a new tab)
- Microsoft remediation guidance (opens in a new tab)
- Microsoft security update · 5130034 (opens in a new tab)
- Microsoft remediation guidance (opens in a new tab)
- Microsoft security update · 5130036 (opens in a new tab)
- Microsoft remediation guidance (opens in a new tab)
- Microsoft security update · Release Notes (opens in a new tab)
- Microsoft security update · 5130035 (opens in a new tab)
- Microsoft remediation guidance (opens in a new tab)
Managed by GTP?
Griffin Technology Partners managed customers may receive additional environment-specific security guidance and remediation assistance through their managed services relationship.
Security bulletins are provided for informational purposes and compiled from authoritative public sources. Vulnerability applicability varies by environment. Validate affected products, configuration, compatibility requirements, and vendor guidance before making production changes.