CVE-2026-27607 HIGH

CVE-2026-27607: RustFS's Missing Post Policy Validation leads to Arbitrary Object Write

Vendor Rustfs
Product rustfs
Weakness CWE-20 · Input validation
Published February 25, 2026
Last update February 25, 2026

CVSS base score

8.1/10
Attack vector Network
Attack complexity Low
Privileges required Low
User interaction None
Confidentiality None
Integrity High

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H

What the vulnerability does

01Description

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.

Key dates

02Disclosure timeline

February 25, 2026 CVE published
February 25, 2026 Record updated