CVE-2026-27607

RustFS's Missing Post Policy Validation leads to Arbitrary Object Write

State: Published
Severity: 8.1 High
Published: Feb 25, 2026
Updated: Feb 25, 2026
Reserved: Feb 20, 2026

Description

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.

Scores

CVSS	Score	Vector	Source
3.1	8.1 High	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H	GitHub_M

Weaknesses

CWE-20 Improper Input Validation
CWE-863 Incorrect Authorization

Affected Products

Product	Versions
rustfsrustfs	>= 1.0.0-alpha.56, < 1.0.0-alpha.83Affected

References

https://github.com/rustfs/rustfs/security/advisories/GHSA-w5fh-f8xh-5x3p

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