by Kastro
Paper/Archive/CVE-2026-27607

CVE-2026-27607

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

EPSS 0.4%CVSS 9.1
critical.is priorityof 100
34
CVSS 9.1 (NVD)9.1 / 10 × 3027.3Not in CISA KEV+300.0EPSS percentile 30.8.308 × 206.2No public exploit+100.0SSVC exploitation: none+100.0
Description · from the CVE record

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

ProductAffectedFixed inSource
rustfs>= 1.0.0-alpha.56, < 1.0.0-alpha.83–CNA

Scores by source

NVD9.1CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H
GitHub_M (CNA)8.1CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H
CISA ADPSSVCExploitation: none · Automatable: no · Technical impact: total

References

refgithub.com/rustfs/rustfs/security/advisories/GHSA-w5fh-f8xh-5x3p