CVE-2026-55189

RustFS: FTP frontend skips IAM authorization on object reads

State: Published
Severity: 7.7 High
Published: Jun 26, 2026
Updated: Jun 29, 2026
Reserved: Jun 16, 2026

Description

RustFS is a distributed object storage system built in Rust. From 1.0.0-alpha.1 until 1.0.0-beta.9, when the FTP frontend is enabled, the FTP read and probe handlers dispatch directly to the storage backend without ever calling the IAM authorization function that the FTP write/list handlers (and the entire HTTP S3 path) use. As a result, any user who can authenticate to the FTP listener — including a user whose IAM policy contains an explicit Deny on s3:GetObject — can read (RETR) and stat (SIZE/MDTM) any object in any bucket, and probe any bucket (CWD), completely regardless of their IAM policy. This vulnerability is fixed in 1.0.0-beta.9.

Scores

CVSS	Score	Vector	Source
3.1	7.7 High	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N	GitHub_M

Weaknesses

CWE-862 Missing Authorization
CWE-863 Incorrect Authorization

Affected Products

Product	Versions
rustfsrustfs	>= 1.0.0-alpha.1, <= 1.0.0-beta.8Affected

References

https://github.com/rustfs/rustfs/security/advisories/GHSA-3g29-xff2-92vp

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