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RustfsApplication

CVE-2026-27607

CRITICAL · 9.1 CVSS v3.1 Published 2026-02-25
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

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. In versions 1.0.0-alpha.56 through 1.0.0-alpha.82, RustFS does not validate policy conditions in presigned POST uploads (PostObject), allowing attackers to bypass content-length-range, starts-with, and Content-Type constraints. This enables unauthorized file uploads exceeding size limits, uploads to arbitrary object keys, and content-type spoofing, potentially leading to storage exhaustion, unauthorized data access, and security bypasses. Version 1.0.0-alpha.83 fixes the issue.

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 versions 1.0.0-alpha.56 through 1.0.0-alpha.82 fail to validate policy conditions (content-length-range, starts-with, and Content-Type) in presigned POST (PostObject) uploads, allowing attackers to bypass upload restrictions and upload files exceeding size limits, to arbitrary object keys, or with spoofed content types.

MitigationUpgrade to RustFS version 1.0.0-alpha.83 or later, which includes proper validation of presigned POST policy conditions.

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

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
RustfsApplication
Affected:= 1.0.0

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
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
High

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

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 and version
    Run 'cargo list rustfs' or check your Cargo.lock/Cargo.toml for the rustfs crate version, or query the binary if deployed
    Affected if The installed version is 1.0.0-alpha.56 through 1.0.0-alpha.82
  2. Verify presigned POST uploads are in use
    Search your codebase for PostObject API calls, presigned POST form uploads, or policy configuration involving 'content-length-range', 'starts-with', or 'Content-Type' conditions
    Affected if Your application uses presigned POST uploads with policy conditions that rely on RustFS validation
  3. Inspect upload policy configuration
    Review any presigned POST policy definitions in your application to see if content-length-range, starts-with, or Content-Type restrictions are defined but not being enforced server-side
    Affected if You have defined policy conditions that RustFS should enforce but the server-side validation may be bypassed due to the bug

You are affected if RustFS version 1.0.0-alpha.56 through 1.0.0-alpha.82 is installed AND your application uses presigned POST uploads with content-length-range, starts-with, or Content-Type policy conditions.

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-alpha.83 or later, which includes proper validation of presigned POST policy conditions.

Recommended fix High confidence

Upgrade to RustFS version 1.0.0-alpha.83 or later

  1. 1. Identify the current RustFS version by checking the deployed binary or dependency manifest (e.g., Cargo.toml).
  2. 2. If running any version from 1.0.0-alpha.56 through 1.0.0-alpha.82, plan for immediate upgrade.
  3. 3. Upgrade RustFS to version 1.0.0-alpha.83 or later by updating the version in your dependency manager (e.g., Cargo.toml: rustfs = "1.0.0-alpha.83").
  4. 4. Rebuild and redeploy the RustFS service with the updated version.
  5. 5. Verify the upgrade was successful by checking the runtime version.
  6. 6. Test presigned POST (PostObject) uploads to confirm policy validation (content-length-range, starts-with, Content-Type) is now enforced correctly.
Caveat Alpha releases may have stability risks; test thoroughly in staging before production deployment

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

Fix this in Rustfs Scoped from the published advisory
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing4.0 h
  • Review / QA3.0 h
16.0 hours of engineering $2,820
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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-2026-27607 in production — separate from our analysis above.

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What this is

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What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
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