CVE-2026-27607
RustFS's Missing Post Policy Validation leads to Arbitrary Object Write
- Published
- Feb 25, 2026
- Updated
- Feb 25, 2026
- Assigning CNA
- GitHub_M
- Evidence observed
- Aug 28, 2026
Primary CVSS
nvd · CVSS 3.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:HLow · next 30 days
- Percentile
- 34.4%
- Model date
- Oct 17, 2026
EPSS is a statistical estimate, not a certainty or a measure of impact. Combine it with CVSS, KEV status, exposure and your environment.
Summary
RustFS is a distributed object storage system built in Rust. In versions 1.0.0-alpha.56 through 1.0.0-alpha.82, RustFS does not validate policy conditions in presigned POST uploads (PostObject), allowing attackers to bypass content-length-range, starts-with, and Content-Type constraints. This enables unauthorized file uploads exceeding size limits, uploads to arbitrary object keys, and content-type spoofing, potentially leading to storage exhaustion, unauthorized data access, and security bypasses. Version 1.0.0-alpha.83 fixes the issue.
Sources
- CVE-2026-PoCsResearch
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