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

Description (CNA)

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.

Affected (CNA)

Vendor / product	Versions
rustfs / rustfs	affected >= 1.0.0-alpha.56, < 1.0.0-alpha.83

CWE

CWE-20, CWE-863

References

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

ADP enrichment

CISA-ADP

No English description supplied.

No references supplied.