I am building an S3 client [1] where I have a test matrix that tests against common S3 implementations, including RustFS.
That test matrix uncovered that post policies were only checked for exsitence and a valid signature, not if the request actually conforms to the signed policy. That was an arbitrary object write resulting in CVE-2026-27607 [2].
In the very first issue for this bug [3], it seemed that the authors of the S3 implementation didn't know the difference between the content-length of GetObject and content-length-range of a PostObject. That was kind of a bummer and leads me to advise all my friends not to use rustfs, though I like what they are doing in principal (building a Minio alternative).
I am writing an s3 server, just checked, have detailed tests for content-length-range. I found that Ceph was the only open source implementation with decent tests, and I ported these as my first stages of implementation, although I have since added a lot more. Notionally rustfs say they use the ceph test suite, but not sure how often and completely, they certainly had big conformance gaps.
That test matrix uncovered that post policies were only checked for exsitence and a valid signature, not if the request actually conforms to the signed policy. That was an arbitrary object write resulting in CVE-2026-27607 [2].
In the very first issue for this bug [3], it seemed that the authors of the S3 implementation didn't know the difference between the content-length of GetObject and content-length-range of a PostObject. That was kind of a bummer and leads me to advise all my friends not to use rustfs, though I like what they are doing in principal (building a Minio alternative).
[1]: https://github.com/nikeee/lean-s3 [2]: https://github.com/rustfs/rustfs/security/advisories/GHSA-w5... [3]: https://github.com/rustfs/rustfs/issues/984