CVE-2026-55189 RustFS: FTP frontend skips IAM authorization on object reads
Authenticated FTP users can bypass IAM policies to read any object or probe buckets in RustFS when the FTP frontend is enabled.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-55189?
CVE-2026-55189 is a high-severity missing authorization vulnerability in rustfs, published on 26 Jun 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official 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.
Which versions are affected by CVE-2026-55189?
How do I fix CVE-2026-55189?
No fix has been published for CVE-2026-55189 yet. Limit exposure of the affected software until one is available.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2026-55189 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-55189 exists.
Sources
Also known as GHSA-3g29-xff2-92vp.