CVE-2026-39399

CRITICAL
2026-04-14 [email protected]
9.6
CVSS 3.1
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CVSS VectorNVD

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:H
Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Changed
Confidentiality
None
Integrity
High
Availability
High

Lifecycle Timeline

2
Re-analysis Queued
Apr 17, 2026 - 15:52 vuln.today
cvss_changed
Analysis Generated
Apr 15, 2026 - 01:12 vuln.today

DescriptionNVD

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.

AnalysisAI

Cross-package metadata injection in NuGet Gallery backend allows authenticated attackers to achieve remote code execution and arbitrary blob storage writes through crafted .nuspec files. Attackers exploit URI fragment injection via unsanitized package identifiers to control blob paths in the storage container, enabling tampering of existing content beyond .nupkg files. …

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RemediationAI

Within 24 hours: Identify all NuGet Gallery instances in your environment and confirm current deployment version; review recent package uploads for suspicious metadata patterns or storage modifications. Within 7 days: Apply vendor-released patch from commit 0e80f87628349207cdcaf55358491f8a6f1ca276 to all NuGet Gallery deployments; conduct post-patch validation testing. …

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CVE-2026-39399 vulnerability details – vuln.today

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