Microsoft .NET: Link following enables local privilege escalation
Summary
Microsoft's .NET runtime does not properly resolve links before accessing files (CWE-59, link following), including named-mutex and shared-memory paths on Unix-like systems. An authorized local user can abuse this to elevate privileges on the affected host. Exploitation requires a local account and is not reachable from the internet. Microsoft has released fixed versions, and no public exploit or active exploitation has been reported.
Affected
- Microsoft .NET 8.0: 8.0.0 to before 8.0.32
- Microsoft .NET 9.0: 9.0.0 to before 9.0.21
- Microsoft .NET 10.0: 10.0.0 to before 10.0.13
- Microsoft .NET 11.0: 11.0.0 to before 11.0.0-rc.2
- Visual Studio 2022 version 17.14: 17.14.0 to before 17.14.42
- Visual Studio 2026 version 18.10: 18.10.0 to before 18.10.4
- Windows: Unconfirmed. A secondary source says Windows is not affected; check the MSRC page.
Fixed in
- .NET runtimes 8.0.32, 9.0.21, 10.0.13 and 11.0.0-rc.2 (matching SDKs per vendor announcement)
- Visual Studio 17.14.42 and 18.10.4 (per the official CVE record)
- Linux distributions: use your distribution's errata for the dotnet packages
Workaround
Unknown. Microsoft offers a patch rather than a workaround for supported versions.
Exploitation
- No known exploitation in the wild. CISA SSVC exploitation: none. Not listed in CISA KEV.
- No public proof-of-concept found. EPSS is about 0.4%.
Our recommendation
- Update .NET runtimes and SDKs to the fixed versions, starting with multi-user Linux and macOS hosts, shared CI runners and container build hosts.
- Check installed Visual Studio versions and confirm Windows exposure on the MSRC page.
- Restrict local shell access on affected hosts and review the directories written by .NET services.
- Roll out the update on other systems within the normal patch cycle.
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) msrc.microsoft.com
- GitHub Advisory GHSA-w6wh-p4g7-mpj2 github.com
- .NET announcement (fixed versions) github.com
- Red Hat Bugzilla bugzilla.redhat.com
- OSV (Ubuntu) osv.dev
- HeroDevs vulnerability directory www.herodevs.com
- OpenCVE app.opencve.io
- VulDB vuldb.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, 00:58.
Original description (NVD)
Improper link resolution before file access ('link following') in .NET allows an authorized attacker to elevate privileges locally.
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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