Critical severity · published May 28, 2026
CVE-2026-45039
RustFS: Internode RPC HMAC secret falls back to public default credential, enabling peer impersonation
9.8
CVSS
0.3%
EPSS
No
On KEV
Description
RustFS is a distributed object storage system built in Rust. Prior to 1.0.0-beta.2, the internode RPC layer authenticates every request with an HMAC-SHA256 signature using a shared secret. The function that produces this secret, get_shared_secret() in crates/ecstore/src/rpc/http_auth.rs, falls back to the public, source-tree-embedded DEFAULT_SECRET_KEY = "rustfsadmin" when neither the RUSTFS_RPC_SECRET environment variable nor the global S3 secret key has been configured. This vulnerability is fixed in 1.0.0-beta.2.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.3% · higher than 19% 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.2 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-45039
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-45039
github.com
https://github.com/rustfs/rustfs/security/advisories/GHSA-r5qv-rc46-hv8q
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