ASP.NET Core Denial of Service Vulnerability

Check whether my systems are affected by CVE-2026-109478 (ASP.NET Core Denial of Service Vulnerability), using the cve.now data below.

Rules: work read-only. Do not run exploit code, proof-of-concept scripts or scanners that send attack payloads, and do not change any configuration, package, image or deployment. Report findings only.

What cve.now has for CVE-2026-109478 (entry last updated 2026-11-10):
Affected:
- Microsoft .NET 8.0 installed on Linux: from 8.0.0, fixed in 8.0.34
- Microsoft .NET 8.0 installed on Mac OS: from 8.0.0, fixed in 8.0.34
- Microsoft .NET 8.0 installed on Windows: from 8.0.0, fixed in 8.0.34
- Microsoft .NET 9.0 installed on Linux: from 9.0.0, fixed in 9.0.0-preview.4.24266.19
- Microsoft .NET 9.0 installed on Mac OS: from 9.0.0, fixed in 9.0.0-preview.4.24266.19
- Microsoft .NET 9.0 installed on Windows: from 9.0.0, fixed in 9.0.0-preview.4.24266.19
- Microsoft Microsoft Visual Studio 2022 version 17.14: from 17.14.0, fixed in 17.14.45
- Microsoft Microsoft Visual Studio 2026 version 18.11: from 18.11.0, fixed in 18.11.4
- Microsoft Microsoft Visual Studio 2026 version 18.12: from 18.12.0, fixed in 18.12.0
Fixed versions: 8.0.34, 9.0.0-preview.4.24266.19, 17.14.45, 18.11.4, 18.12.0.
Setup: unknown whether the bug needs a non-default feature or setting. Check the advisory.
CISA KEV: CVE-2026-109478 is not listed as of cve.now's last read.
This KEV status is for CVE-2026-109478 only. If you also check another CVE, look up its own KEV status; never assume it from this one.

How to check:
- Installed software: check what is actually running, not what a repo declares. Read the version from each host, container image and Kubernetes node (the binary's version output, the OS package database, image layers), and check whether the conditions above hold there. Distribution packages may carry a backported fix under an older version number; confirm against the distribution's own advisory.

Verify against the linked advisories before concluding, and cite the date you read each one:
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-109478
Do not conclude an asset is unaffected unless you checked it and the evidence covers both its version and the conditions above. If you could not check something, mark it unknown and say what is missing.

Report a table with one row per asset and these columns: Asset | Version or build | Status (affected, fixed, not applicable, unknown) | Compensating controls | Exposure (internet-facing, internal, none) | Evidence | Next action.

Entry: https://cve.now/CVE-2026-109478
For follow-up questions, use the cve.now MCP server at https://mcp.cve.now/mcp (no authentication), for example get_vulnerability with id CVE-2026-109478.