Description
RustFS is a distributed object storage system built in Rust. From 1.0.0-alpha.64 until 1.0.0-rc.1, RustFS external OPA authorization enabled by RUSTFS_POLICY_PLUGIN_URL in crates/iam/src/sys.rs sets PreparedIamAuth.needs_existing_object_tag incorrectly for PreparedIamMode::Opa, causing maybe_merge_object_tag_conditions to omit s3:ExistingObjectTag/* values and allowing authenticated users to bypass tag-based policy restrictions. This issue is fixed in version 1.0.0-rc.1.
References5
- github.com/rustfs/rustfs/blob/380ed40b471887014fe21d069b61df9ea…
- github.com/rustfs/rustfs/commit/98d3619613722308498494d412797a5…
- github.com/rustfs/rustfs/releases/tag/1.0.0-rc.1
- github.com/rustfs/rustfs/security/advisories/GHSA-5w8r-p896-6vq2
- github.com/rustfs/rustfs/security/advisories/GHSA-5w8r-p896-6vq2
Metrics
- CVSS 3.1
-
7.5
HIGH
Score source: CNA
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H - EPSS — exploit probability
- 0% percentile: 41 · as of 12 November 2026
- CWE
- CWE-863
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.