CVE-2026-49991 RustFS Snowball Auto-Extract: Path Traversal allows cross-bucket object injection
Authenticated users can exploit path traversal in Snowball auto-extract to write objects into other users' buckets, breaking multi-tenant isolation.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-49991?
CVE-2026-49991 is a high-severity path traversal vulnerability in rustfs, published on 26 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
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.
Which versions are affected by CVE-2026-49991?
How do I fix CVE-2026-49991?
No fix has been published for CVE-2026-49991 yet. Limit exposure of the affected software until one is available.
Upgrade, and resolve every user-supplied path against an allowed base folder before opening it. More about Path traversal.
Is CVE-2026-49991 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-49991 exists.
Sources
Also known as GHSA-f4vq-9ffr-m8m3.