.NET flaws enable DoS and data integrity attacks
Multiple vulnerabilities in Microsoft .NET 8.0, 9.0, and 10.0 on Linux and macOS allow remote attackers to cause denial of service and compromise data integrity.
Sourcecert.ssi.gouv.fr — open the original
What to check
- Applies to
- The 2 CVEs named below. Whether you run an affected version is not assessed: check the versions the source lists.
- Exploitation
- No exploitation in the wild and no public exploit is recorded for the CVEs named.
The French CERT (CERT-FR) has disclosed multiple security vulnerabilities affecting Microsoft .NET Framework and ASP.NET Core across versions 8.0, 9.0, and 10.0. The flaws impact installations on Linux and macOS platforms, enabling attackers to remotely trigger denial of service conditions and compromise data integrity. Affected versions include .NET 8.0 prior to 8.0.28, .NET 9.0 prior to 9.0.17, and .NET 10.0 prior to 10.0.9, along with their corresponding ASP.NET Core implementations.
Two CVEs have been assigned to track these vulnerabilities: CVE-2026-45491 and CVE-2026-45591. Microsoft has released patches addressing both issues as part of their June 2026 security updates. Organizations running affected .NET versions on Linux or macOS systems should prioritize applying the available updates to mitigate potential exploitation.
The advisory emphasizes the remote nature of these vulnerabilities, suggesting they may be exploitable over network connections without requiring local access or user interaction. Given the widespread deployment of .NET in enterprise environments, particularly for web applications and APIs, the impact surface is potentially significant across multiple sectors.
Mentioned in this report
Source reporting: https://www.cert.ssi.gouv.fr/avis/CERTFR-2026-AVI-0729
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