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Missing AuthorizationWeakness · CWE-862

CVE-2026-55189

HIGH · 7.7 CVSS v3.1 Published 2026-06-26
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
83/100
Remediation priority · High
Remotely reachable Zero-click 8 weeks old

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
RustFS is a distributed object storage system built in Rust. From 1.0.0-alpha.1 until 1.0.0-beta.9, when the FTP frontend is enabled, the FTP read and probe handlers dispatch directly to the storage backend without ever calling the IAM authorization function that the FTP write/list handlers (and the entire HTTP S3 path) use. As a result, any user who can authenticate to the FTP listener — including a user whose IAM policy contains an explicit Deny on s3:GetObject — can read (RETR) and stat (SIZE/MDTM) any object in any bucket, and probe any bucket (CWD), completely regardless of their IAM policy. This vulnerability is fixed in 1.0.0-beta.9.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

RustFS FTP frontend has a broken access control vulnerability where the FTP read (RETR) and probe (SIZE/MDTM/CWD) handlers bypass IAM authorization entirely, dispatching directly to the storage backend. This allows any authenticated FTP user — including those with explicit IAM Deny on s3:GetObject — to read any object in any bucket regardless of IAM policy.

MitigationUpgrade to RustFS version 1.0.0-beta.9 or later, which includes the IAM authorization check in the FTP read and probe handlers.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Scope
Changed
Confidentiality
High
Integrity
None
Availability
None

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify RustFS installation
    Check for RustFS binary or service: run `which rustfs` or look for rustfs process: `ps aux | grep -i rustfs`. If running as a service, check system service files for rustfs entries.
    Affected if RustFS is present in the environment and FTP access is enabled
  2. Determine RustFS version
    Run `rustfs --version` or check the version from the binary/service manifest. Compare against the affected range: versions prior to 1.0.0-beta.9 are vulnerable.
    Affected if Version is below 1.0.0-beta.9
  3. Verify FTP service is exposed
    Check FTP listener configuration: look for port 21 or configured FTP ports in rustfs config (typically /etc/rustfs/config.yaml or similar). Use `netstat -tlnp | grep ftp` or `ss -tlnp | grep ftp` to detect listening FTP services.
    Affected if FTP service is listening and accessible to users
  4. Confirm IAM authorization is not enforced on FTP handlers
    This requires code inspection or testing: attempt an FTP login with a user that has explicit IAM Deny on s3:GetObject, then issue RETR, SIZE, MDTM, or CWD commands against a protected object. If the command succeeds, the vulnerability is present.
    Affected if An authenticated FTP user with IAM Deny on s3:GetObject can still read objects via RETR or probe commands

A user is affected if RustFS version is below 1.0.0-beta.9 and the FTP service is accessible, allowing authenticated users to bypass IAM policies when using RETR, SIZE, MDTM, or CWD commands.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade to RustFS version 1.0.0-beta.9 or later, which includes the IAM authorization check in the FTP read and probe handlers.

Recommended fix High confidence

Upgrade to RustFS version 1.0.0-beta.9 or later

  1. 1. Identify the currently deployed RustFS version using the system's package manager or deployment documentation
  2. 2. If running a version between 1.0.0-alpha.1 and 1.0.0-beta.8 (inclusive), plan for an upgrade
  3. 3. Upgrade RustFS to version 1.0.0-beta.9 or later
  4. 4. After upgrade, verify that FTP read (RETR), stat (SIZE/MDTM), and bucket probe (CWD) operations now properly enforce IAM authorization
  5. 5. Test with a user having explicit Deny on s3:GetObject to confirm the fix blocks FTP read access
Caveat Review release notes for 1.0.0-beta.9 to check for any breaking changes between the current version and the target version

Generated from the published advisory — verify against the referenced sources before acting.

Have this fixed Scoped from the published advisory
  • Consultation3.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA2.0 h
12.0 hours of engineering $2,130
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-55189 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
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