High severity · published Jun 26, 2026
CVE-2026-49991
RustFS Snowball Auto-Extract: Path Traversal allows cross-bucket object injection
8.6
CVSS
0.4%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
High
Availability
None
Scope
Changed
Exploitation
Is it being used?
Exploit prediction (EPSS)0.4% · higher than 36% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
RU
rustfs · rustfs
1.0.0-beta.4 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-49991
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-49991
github.com
https://github.com/rustfs/rustfs/security/advisories/GHSA-f4vq-9ffr-m8m3
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