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CVE-2026-39399

NuGet Gallery: Arbitrary Blob Overwrite via Nuspec Confusion and URI Fragment Truncation

Published: Apr 14, 2026Updated: Apr 17, 2026 Sources: CVE List NVDCWE-20
NVD MITRE
9.6CVSSCRITICAL
EPSS Score
0.5%
Top 59.7%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
No Fix Available

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 Vector Breakdown

AV:NAC:LPR:LUI:NS:CC:NI:HA:H
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:LPrivileges Required
Low
UI:NUser Interaction
None
Scope
S:CScope
Changed
Impact
C:NConfidentiality
None
I:HIntegrity
High
A:HAvailability
High
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Weaknesses

CWE-20CWE-22

Affected Products

NuGetGalleryNuGetOSS Libraries
nugetpackage-ecosystemOSS Libraries

Attack Graph

Products CVE Techniques Tactics

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Exploitability

No known exploits, KEV entries, or remediation guidance available for this vulnerability yet.

MITRE ATT&CK

3 techniques
Collection
Discovery
Initial Access
View detailed technique mapping

References

https://github.com/NuGet/NuGetGallery/security/advisories/GHSA-9r3h-v4hx-rhfr
github.com
https://github.com/NuGet/NuGetGallery/commit/0e80f87628349207cdcaf55358491f8a6f1ca276
github.com

Timeline

Published
Apr 14, 2026
Last Updated
Apr 17, 2026

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