CVE-2026-49991: Rustfs

High severity, CVSS 8.6. EPSS: 0.4% chance of exploitation in the next 30 days.

RustFS is a distributed object storage system built in Rust. In 1.0.0-beta.4, authenticated users with only PutObject permission on their own bucket can exploit a path traversal vulnerability in the Snowball auto-extract feature to write arbitrary objects into other users' buckets, completely breaking multi-tenant isolation. The vulnerability chains three flaws: No ../ sanitization in tar entry key normalization; IAM wildcard matching uses raw (uncleaned) paths; and Filesystem path cleaning resolves ../ across bucket boundaries.

Affected products

• Rustfs Rustfs: version 1.0.0-beta.4 only

Published 2026-06-26. Last modified 2026-06-29.