VulnerabilityAwaiting Analysis

CVE-2026-39399

A security vulnerability exists in the NuGetGallery backend job’s handling of .nuspec files within NuGet packages.

CRITICAL 9.6EPSS 0.53%

Does this matter?

High impact if exploited, but EPSS currently rates exploitation as unlikely (0.53%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.

Description

NuGet Gallery is a package repository that powers nuget.org. A security vulnerability exists in the NuGetGallery backend job’s handling of .nuspec files within NuGet packages. An attacker can supply a crafted nuspec file with malicious metadata, leading to cross package metadata injection that may result in remote code execution (RCE) and/or arbitrary blob writes due to insufficient input validation. The issue is exploitable via URI fragment injection using unsanitized package identifiers, allowing an attacker to control the resolved blob path. This enables writes to arbitrary blobs within the storage container, not limited to .nupkg files, resulting in potential tampering of existing content. This issue has been patched in commit 0e80f87628349207cdcaf55358491f8a6f1ca276.

CVSS 3.1: 9.6 CRITICALCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:H
EPSS: 0.53% probability · 43th percentile
CISA KEV: Not listed
Weakness: CWE-20, CWE-22
Source: security-advisories@github.com

References

Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.