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Incorrect AuthorizationWeakness · CWE-863

CVE-2026-45042

HIGH · 7.1 CVSS v4.0 Published 2026-05-28
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
77/100
Remediation priority · High
Remotely reachable 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. Prior to 1.0.0-beta.2, improper authorization in the UploadPartCopy operation allows copying objects across buckets without enforcing destination bucket restrictions on allowed copy sources. The implementation validates GetObject permission on the source bucket and PutObject on the destination bucket independently, but does not enforce any policy constraints on whether the destination bucket permits the specified copy source. This enables unauthorized cross-bucket data movement. This vulnerability is fixed in 1.0.0-beta.2.

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 prior to 1.0.0-beta.2 contain an improper authorization vulnerability in the UploadPartCopy operation that allows cross-bucket object copying without enforcing destination bucket restrictions on copy sources. The implementation validates GetObject permission on the source bucket and PutObject on the destination bucket independently, but fails to verify whether the destination bucket's policy permits the specified copy source, enabling unauthorized data movement between buckets.

MitigationUpgrade to RustFS version 1.0.0-beta.2 or later. Additionally, review and enforce bucket policies to restrict cross-bucket copy operations until the upgrade is completed.

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
Authentication
X
User interaction
None
Scope
X

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

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
    Locate the RustFS binary or library in your environment and query its version using 'rustfs --version', 'rustfs -v', or checking the library manifest file for the installed version string
    Affected if The version is prior to 1.0.0-beta.2 (e.g., 1.0.0-beta.1, 1.0.0-alpha.x, or any earlier release)
  2. Confirm UploadPartCopy operation is in use
    Review your application's S3 API call logs or code to determine if any UploadPartCopy or multipart copy-from-copy-source operations are being performed between buckets
    Affected if UploadPartCopy or similar cross-bucket copy operations are actively used in your environment
  3. Examine destination bucket policies for copy-source restrictions
    Inspect the bucket policy JSON for the destination bucket (using S3 API: GET bucket policy) and look for any Deny statements with s3:CopySource conditions or explicit cross-bucket copy restrictions
    Affected if The destination bucket policy does NOT contain explicit restrictions on allowed copy sources, or allows copying from any source (null/empty policy means unrestricted)
  4. Verify cross-bucket copy access controls
    Check the IAM or access policy configuration to determine if there are any resource-based policies on the destination bucket that restrict which source buckets.objects can be copied into it
    Affected if No destination-bucket-specific policy exists to limit copy sources, allowing any authenticated principal to copy from any source bucket into the destination

You are affected if RustFS version is prior to 1.0.0-beta.2 AND UploadPartCopy operations are used, without compensating bucket policy controls restricting copy sources on the destination bucket.

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.2 or later. Additionally, review and enforce bucket policies to restrict cross-bucket copy operations until the upgrade is completed.

Recommended fix High confidence

1.0.0-beta.2

  1. Identify the current version of RustFS being used in your deployment
  2. Update RustFS to version 1.0.0-beta.2 or later
  3. Verify the upgrade was successful by checking the installed version
  4. Test the UploadPartCopy operation to confirm cross-bucket copy restrictions are now properly enforced
  5. Review any cross-bucket copy policies to ensure they align with intended access controls
Caveat Upgrading to a beta release (1.0.0-beta.2) may introduce compatibility or stability considerations; thoroughly test in a staging environment before production deployment

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

Have this fixed Scoped from the published advisory
  • Consultation3.0 h
  • Implementation12.0 h
  • Testing6.0 h
  • Review / QA3.0 h
24.0 hours of engineering $4,200
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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-2026-45042 in production — separate from our analysis above.

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