CVE-2026-70188 ASP.NET Core Security Feature Bypass Vulnerability
Critical 9.1
Published
Updated
Check this codebase for CVE-2026-70188 and fix it if it is affected.
What it is: CVE-2026-70188 is a critical vulnerability in Microsoft ASP.NET Core 10.0, published on 13 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-70188 in the wild and no public exploit code.
Affected packages and fixed versions:
- Microsoft.AspNetCore.App.Runtime.linux-arm (NuGet): affected from 10.0.0; fixed in 10.0.13
- Microsoft.AspNetCore.App.Runtime.linux-arm (NuGet): affected from 10.0.0; fixed in 10.0.13
- Microsoft.AspNetCore.App.Runtime.linux-arm (NuGet): affected from 11.0.0-preview.1; fixed in 11.0.0-rc.2
- Microsoft.AspNetCore.App.Runtime.linux-arm (NuGet): affected from 11.0.0-preview.1; fixed in 11.0.0-rc.2
- Microsoft.AspNetCore.App.Runtime.linux-arm (NuGet): affected from 8.0.0; fixed in 8.0.32
- Microsoft.AspNetCore.App.Runtime.linux-arm (NuGet): affected from 8.0.0; fixed in 8.0.32
- Microsoft.AspNetCore.App.Runtime.linux-arm (NuGet): affected from 9.0.0; fixed in 9.0.21
- Microsoft.AspNetCore.App.Runtime.linux-arm (NuGet): affected from 9.0.0; fixed in 9.0.21
- Microsoft.AspNetCore.App.Runtime.linux-arm64 (NuGet): affected from 10.0.0; fixed in 10.0.13
- Microsoft.AspNetCore.App.Runtime.linux-arm64 (NuGet): affected from 10.0.0; fixed in 10.0.13
- Microsoft.AspNetCore.App.Runtime.linux-arm64 (NuGet): affected from 11.0.0-preview.1; fixed in 11.0.0-rc.2
- Microsoft.AspNetCore.App.Runtime.linux-arm64 (NuGet): affected from 11.0.0-preview.1; fixed in 11.0.0-rc.2
Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.
Reference: https://insights.sbomify.com/CVE-2026-70188/ (Markdown: https://insights.sbomify.com/CVE-2026-70188/index.md)
An attacker can bypass security features via HTTP request smuggling in ASP.NET Core, requiring a patch to mitigate.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-70188?
CVE-2026-70188 is a critical vulnerability in Microsoft ASP.NET Core 10.0, published on 13 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Inconsistent interpretation of http requests ('http request/response smuggling') in ASP.NET Core allows an unauthorized attacker to bypass a security feature over a network.
Weakness: CWE-444
Which versions are affected by CVE-2026-70188?
40 open source packages ship an affected version, including Microsoft.AspNetCore.App.Runtime.linux-arm, Microsoft.AspNetCore.App.Runtime.linux-arm64 and Microsoft.AspNetCore.App.Runtime.linux-musl-arm.
| Package | Affected | Fixed in |
|---|---|---|
Microsoft.AspNetCore.App.Runtime.linux-arm NuGet | From 10.0.0 | 10.0.13 |
Microsoft.AspNetCore.App.Runtime.linux-arm NuGet | From 10.0.0 | 10.0.13 |
Microsoft.AspNetCore.App.Runtime.linux-arm NuGet | From 11.0.0-preview.1 | 11.0.0-rc.2 |
Microsoft.AspNetCore.App.Runtime.linux-arm NuGet | From 11.0.0-preview.1 | 11.0.0-rc.2 |
Microsoft.AspNetCore.App.Runtime.linux-arm NuGet | From 8.0.0 | 8.0.32 |
Microsoft.AspNetCore.App.Runtime.linux-arm NuGet | From 8.0.0 | 8.0.32 |
34 more packages
Microsoft.AspNetCore.App.Runtime.linux-arm NuGet | From 9.0.0 | 9.0.21 |
Microsoft.AspNetCore.App.Runtime.linux-arm NuGet | From 9.0.0 | 9.0.21 |
Microsoft.AspNetCore.App.Runtime.linux-arm64 NuGet | From 10.0.0 | 10.0.13 |
Microsoft.AspNetCore.App.Runtime.linux-arm64 NuGet | From 10.0.0 | 10.0.13 |
Microsoft.AspNetCore.App.Runtime.linux-arm64 NuGet | From 11.0.0-preview.1 | 11.0.0-rc.2 |
Microsoft.AspNetCore.App.Runtime.linux-arm64 NuGet | From 11.0.0-preview.1 | 11.0.0-rc.2 |
Microsoft.AspNetCore.App.Runtime.linux-arm64 NuGet | From 8.0.0 | 8.0.32 |
Microsoft.AspNetCore.App.Runtime.linux-arm64 NuGet | From 8.0.0 | 8.0.32 |
Microsoft.AspNetCore.App.Runtime.linux-arm64 NuGet | From 9.0.0 | 9.0.21 |
Microsoft.AspNetCore.App.Runtime.linux-arm64 NuGet | From 9.0.0 | 9.0.21 |
Microsoft.AspNetCore.App.Runtime.linux-musl-arm NuGet | From 10.0.0 | 10.0.13 |
Microsoft.AspNetCore.App.Runtime.linux-musl-arm NuGet | From 10.0.0 | 10.0.13 |
Microsoft.AspNetCore.App.Runtime.linux-musl-arm NuGet | From 11.0.0-preview.1 | 11.0.0-rc.2 |
Microsoft.AspNetCore.App.Runtime.linux-musl-arm NuGet | From 11.0.0-preview.1 | 11.0.0-rc.2 |
Microsoft.AspNetCore.App.Runtime.linux-musl-arm NuGet | From 8.0.0 | 8.0.32 |
Microsoft.AspNetCore.App.Runtime.linux-musl-arm NuGet | From 8.0.0 | 8.0.32 |
Microsoft.AspNetCore.App.Runtime.linux-musl-arm NuGet | From 9.0.0 | 9.0.21 |
Microsoft.AspNetCore.App.Runtime.linux-musl-arm NuGet | From 9.0.0 | 9.0.21 |
Microsoft.AspNetCore.App.Runtime.linux-musl-arm64 NuGet | From 10.0.0 | 10.0.13 |
Microsoft.AspNetCore.App.Runtime.linux-musl-arm64 NuGet | From 10.0.0 | 10.0.13 |
Microsoft.AspNetCore.App.Runtime.linux-musl-arm64 NuGet | From 11.0.0-preview.1 | 11.0.0-rc.2 |
Microsoft.AspNetCore.App.Runtime.linux-musl-arm64 NuGet | From 11.0.0-preview.1 | 11.0.0-rc.2 |
Microsoft.AspNetCore.App.Runtime.linux-musl-arm64 NuGet | From 8.0.0 | 8.0.32 |
Microsoft.AspNetCore.App.Runtime.linux-musl-arm64 NuGet | From 8.0.0 | 8.0.32 |
Microsoft.AspNetCore.App.Runtime.linux-musl-arm64 NuGet | From 9.0.0 | 9.0.21 |
Microsoft.AspNetCore.App.Runtime.linux-musl-arm64 NuGet | From 9.0.0 | 9.0.21 |
Microsoft.AspNetCore.App.Runtime.linux-musl-x64 NuGet | From 10.0.0 | 10.0.13 |
Microsoft.AspNetCore.App.Runtime.linux-musl-x64 NuGet | From 10.0.0 | 10.0.13 |
Microsoft.AspNetCore.App.Runtime.linux-musl-x64 NuGet | From 11.0.0-preview.1 | 11.0.0-rc.2 |
Microsoft.AspNetCore.App.Runtime.linux-musl-x64 NuGet | From 11.0.0-preview.1 | 11.0.0-rc.2 |
Microsoft.AspNetCore.App.Runtime.linux-musl-x64 NuGet | From 8.0.0 | 8.0.32 |
Microsoft.AspNetCore.App.Runtime.linux-musl-x64 NuGet | From 8.0.0 | 8.0.32 |
Microsoft.AspNetCore.App.Runtime.linux-musl-x64 NuGet | From 9.0.0 | 9.0.21 |
Microsoft.AspNetCore.App.Runtime.linux-musl-x64 NuGet | From 9.0.0 | 9.0.21 |
How do I fix CVE-2026-70188?
Upgrade Microsoft.AspNetCore.App.Runtime.linux-arm to a fixed version for your release line: 10.0.13, 11.0.0-rc.2, 8.0.32 or 9.0.21.
Is CVE-2026-70188 being exploited?
There is no known exploitation of CVE-2026-70188 in the wild and no public exploit code.
Sources
Also known as CLEANSTART-2026-IO26222, GHSA-fpq8-4vhr-rcxx, UBUNTU-CVE-2026-70188.