NuGet Gallery nuspec File injection

Summaryinfo

A vulnerability identified as problematic has been detected in NuGet Gallery. Affected by this issue is some unknown functionality of the component nuspec File Handler. The manipulation leads to injection. This vulnerability is documented as CVE-2026-39399. The attack can be initiated remotely. There is not any exploit available. To fix this issue, it is recommended to deploy a patch.

Detailsinfo

A vulnerability was found in NuGet Gallery (affected version not known) and classified as problematic. This issue affects some unknown functionality of the component nuspec File Handler. The manipulation with an unknown input leads to a injection vulnerability. Using CWE to declare the problem leads to CWE-74. The product constructs all or part of a command, data structure, or record using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify how it is parsed or interpreted when it is sent to a downstream component. Impacted is integrity, and availability. The summary by CVE is:

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.

It is possible to read the advisory at github.com. The identification of this vulnerability is CVE-2026-39399 since 04/07/2026. The exploitation is known to be easy. The attack may be initiated remotely. The technical details are unknown and an exploit is not publicly available. The attack technique deployed by this issue is T1055 according to MITRE ATT&CK.

Applying the patch 0e80f87628349207cdcaf55358491f8a6f1ca276 is able to eliminate this problem. The bugfix is ready for download at github.com.

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Productinfo

Type

• Photo Gallery Software

Vendor

• NuGet

Name

• Gallery

License

• open-source

CPE 2.3info

• 🔒

CPE 2.2info

• 🔒

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