CVE-2026-27607

HIGH

RustFS 1.0.0-alpha.56-82 - Auth Bypass

Title source: llm
STIX 2.1

Exploitation Summary

EIP tracks 2 public exploits for CVE-2026-27607. PoCs published by SecureWithUmer, nikeee.

AI-analyzed exploit summary This PoC demonstrates a vulnerability in RustFS (v1.0.0-alpha.82) where S3 pre-signed POST conditions are not properly enforced, allowing attackers to bypass content-length, key prefix, and content-type restrictions. The exploit uses AWS SDK to generate pre-signed POST URLs and demonstrates bypass scenarios.

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.

Exploits (2)

github WORKING POC
by SecureWithUmer · c++poc
https://github.com/SecureWithUmer/CVE-2026-PoCs/tree/main/2026/CVE-2026-27607

This PoC demonstrates a vulnerability in RustFS (v1.0.0-alpha.82) where S3 pre-signed POST conditions are not properly enforced, allowing attackers to bypass content-length, key prefix, and content-type restrictions. The exploit uses AWS SDK to generate pre-signed POST URLs and demonstrates bypass scenarios.

Classification
Working Poc 98%
Attack Type
Auth Bypass
Complexity
Moderate
Reliability
Reliable
Target: rustfs:1.0.0-alpha.82
Auth required
Prerequisites: Valid AWS S3 credentials for the target RustFS instance · Network access to the RustFS S3 endpoint · Node.js environment to run the exploit
mistral-large-3 · analyzed Jul 08, 2026 Full analysis →
nomisec WORKING POC
by nikeee · poc
https://github.com/nikeee/CVE-2026-27607

This repository contains a functional proof-of-concept exploit for CVE-2026-27607, demonstrating how an attacker can bypass S3 presigned post policy conditions in RustFS. The exploit includes examples of bypassing content-length-range, key prefix restrictions, and content-type restrictions.

Classification
Working Poc 95%
Attack Type
Auth Bypass
Complexity
Moderate
Reliability
Reliable
Target: RustFS version 1.0.0-alpha.82
Auth required
Prerequisites: Node.js · Docker · Docker Compose · AWS SDK for JavaScript
mistral-large-3 · analyzed Feb 25, 2026 Full analysis →

References (1)

Core 1
Core References

Scores

CVSS v3 8.1
EPSS 0.0027
EPSS Percentile 18.3%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H

CISA SSVC

Vulnrichment
Exploitation none
Automatable no
Technical Impact total

Details

CWE
CWE-20 CWE-863
Status published
Products (2)
crates.io/rustfs 1.0.0-alpha.56 - 1.0.0-alpha.83crates.io
rustfs/rustfs 1.0.0 alpha56 (27 CPE variants)
Published Feb 25, 2026
Tracked Since Feb 25, 2026