CVE-2026-45491: Microsoft Security Advisory CVE-2026-45491 – .NET Tampering Vulnerability

June 16, 2026

Microsoft is releasing this security advisory to provide information about a vulnerability in System.Formats.Tar. This advisory also provides guidance on what developers can do to update their applications to remove this vulnerability.

A tampering vulnerability exists in the TarFile.ExtractToDirectory method where a symlink path traversal enables an attacker to perform arbitrary file writes outside the intended extraction directory.

References

github.com/advisories/GHSA-7q4v-2mr6-5gpx
github.com/dotnet/announcements/issues/404
github.com/dotnet/runtime/security/advisories/GHSA-7q4v-2mr6-5gpx
msrc.microsoft.com/update-guide/vulnerability/CVE-2026-45491
nvd.nist.gov/vuln/detail/CVE-2026-45491

Code Behaviors & Features

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