CVE-2026-39399NuGet Gallery: Arbitrary Blob Overwrite via Nuspec Confusion and URI Fragment Truncation
Updated under an hour ago ()
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It affects NuGetGallery. Add what you run to find out whether that includes you.
No exploitation reported and no EPSS estimate yet.
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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
- 9.6 CRITICAL (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:H
- Weakness (CWE)
- CWE-20, CWE-22
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- GitHub_M
- NVD analysis
- Awaiting Analysis
- Record last updated
- Apr 15, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.