CVE-2026-45039 RustFS: Internode RPC HMAC secret falls back to public default credential, enabling peer impersonation
Attackers can impersonate peers and escalate privileges in RustFS due to a hardcoded default HMAC secret used when no custom secret is configured.
- 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-2026-45039?
CVE-2026-45039 is a critical vulnerability in rustfs, published on 28 May 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. 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.
Which versions are affected by CVE-2026-45039?
How do I fix CVE-2026-45039?
No fix has been published for CVE-2026-45039 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-45039 being exploited?
There is no known exploitation of CVE-2026-45039 in the wild and no public exploit code.
Sources
Also known as GHSA-r5qv-rc46-hv8q.