Microsoft ASP.NET Core: Denial of service via unbounded resource allocation
Summary
A flaw in ASP.NET Core allows unauthenticated remote attackers to exhaust server resources and cause a denial of service. According to research notes, FileBufferingReadStream eagerly rents buffers during multipart processing, so crafted multipart requests can exhaust memory. No confidentiality or integrity impact is reported, and no user interaction is required.
Affected
- Microsoft ASP.NET Core 8.0: 8.0.0 to before 8.0.32
- Microsoft ASP.NET Core 9.0: 9.0.0 to before 9.0.21
- Microsoft ASP.NET Core 10.0: 10.0.0 to before 10.0.13
- Microsoft Visual Studio 2022 version 17.14: 17.14.0 to before 17.14.42 (third-party tracker, verify on MSRC)
- Microsoft Visual Studio 2026 version 18.10: 18.10.0 to before 18.10.4 (third-party tracker, verify on MSRC)
- .NET 6: Not listed by Microsoft. HeroDevs (third party) states 6.0.0 to 6.0.46 is affected. Unconfirmed.
Fixed in
- ASP.NET Core 8.0.32 or later
- ASP.NET Core 9.0.21 or later
- ASP.NET Core 10.0.13 or later
- Visual Studio 2022 17.14.42 or later (verify on MSRC)
- Visual Studio 2026 18.10.4 or later (verify on MSRC)
- .NET 6: Unknown from Microsoft. HeroDevs names NES for .NET 6.0.47 (paid).
Workaround
Unknown. No vendor workaround is documented in the reviewed sources. Patching is the stated fix.
Exploitation
- Microsoft: not publicly disclosed, not exploited, exploitability assessment "Exploitation Less Likely"
- CISA KEV: not listed
- CISA SSVC: exploitation none, automatable yes, technical impact partial
- EPSS: 0.01056
- No public proof-of-concept found in searches; this does not prove none exists.
Our recommendation
- Inventory all ASP.NET Core applications and Visual Studio installations, including .NET 6 apps.
- Patch ASP.NET Core to 8.0.32, 9.0.21 or 10.0.13 or later, and update Visual Studio to the fixed builds.
- Prioritise internet-facing applications with form or file upload endpoints.
- For .NET 6, confirm support status directly with Microsoft; migrate to a supported version or evaluate paid extended support.
- Consider limiting request and form sizes at the reverse proxy or in Kestrel, and monitor for unusual upload traffic. Test before relying on this.
- Check the NVD record, which is still awaiting analysis.
Information from Microsoft (Patch Tuesday October 2026)
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- Microsoft Security Update Guide msrc.microsoft.com
- Red Hat Bugzilla bugzilla.redhat.com
- Ubuntu Security Notice ubuntu.com
- GitHub .NET announcement issue 459 github.com
- HeroDevs vulnerability directory www.herodevs.com
- NVD record via Vulners vulners.com
Researched and written up in English and German by an AI (Claude by Anthropic) based on NVD, CISA, EPSS and the sources listed. The vendor information is authoritative. Researched on 2 Nov 2026, 19:02.
Original description (NVD)
Allocation of resources without limits or throttling in ASP.NET Core allows an unauthorized attacker to deny service over a network.
NVD references (1)
Sources
The tracker combines official, freely usable data sources – updated continuously:
- NVD (NIST) – CVEs, rating (CVSS), affected products
- CISA KEV – vulnerabilities confirmed by CISA as actively exploited
- CISA Vulnrichment – CISA assessment (SSVC) in the official CVE record
- FIRST EPSS – probability of exploitation
- Microsoft MSRC – Patch Tuesday: vulnerabilities, severity, updates
- PoC-in-GitHub – public proof-of-concept repositories
- Metasploit (Rapid7) – modules of the Metasploit Framework
- Exploit-DB (OffSec) – archive of public exploits (links only)
- Patch days: official vendor pages (linked per vendor) (Vendor patch days)
This product uses data from the NVD API but is not endorsed or certified by the NVD. EPSS data © FIRST.org.
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