Is CVE-2026-45039 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-45039 being exploited in the wild.

How severe is CVE-2026-45039?

Critical severity, with a CVSS score of 9.8, published 28 May 2026.

Which products and versions are affected?

RustFS RustFS Prior to 1.0.0-beta.2.

Is there a fix for CVE-2026-45039?

No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

How is CVE-2026-45039 attacked?

It is attacked over the network, in a hosted service.

Am I affected by CVE-2026-45039?

Check whether anything you run is named in the advisory. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-45039: RustFS hard-coded default HMAC secret in internode RPC layer

CVE-2026-45039 · Severity: critical · CVSS 9.8 · Published 2026-05-28

RustFS is a distributed storage system used to manage large-scale data across multiple servers. A security flaw allows attackers to bypass authentication by using a publicly known default password ("rustfsadmin") that the system automatically uses if not explicitly configured otherwise. This allows an unauthorized person to impersonate a legitimate server in the cluster, potentially leading to the theft, modification, or deletion of stored data.

Quick answers

Is CVE-2026-45039 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-45039 being exploited in the wild.
How severe is CVE-2026-45039?: Critical severity, with a CVSS score of 9.8, published 28 May 2026.
Which products and versions are affected?: RustFS RustFS Prior to 1.0.0-beta.2.
Is there a fix for CVE-2026-45039?: No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2026-45039 attacked?: It is attacked over the network, in a hosted service.
Am I affected by CVE-2026-45039?: Check whether anything you run is named in the advisory. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

RustFS prior to version 1.0.0-beta.2 contains a hard-coded credentials vulnerability (CWE-798/CWE-1392) in its internode RPC layer. The 'get_shared_secret()' function in 'crates/ecstore/src/rpc/http_auth.rs' falls back to a static, source-tree-embedded string ('rustfsadmin') if the 'RUSTFS_RPC_SECRET' environment variable or global S3 secret key is not set. An unauthenticated attacker with network access to the RPC port (typically 7000) can generate valid HMAC-SHA256 signatures using this default key to impersonate a cluster node. This allows the execution of arbitrary RPC commands, bypassing S3-layer access controls and enabling full data exfiltration or manipulation. The issue is fixed in version 1.0.0-beta.2 by removing the fallback mechanism.

Affected products

RustFS RustFS Prior to 1.0.0-beta.2

Timeline

2026-05-09: advisory: GitHub Security Advisory GHSA-r5qv-rc46-hv8q published
2026-05-28: disclosed: CVE-2026-45039 published to NVD

References

https://github.com/rustfs/rustfs/security/advisories/GHSA-r5qv-rc46-hv8q

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