# CVE-2026-45042: RustFS: UploadPartCopy Does Not Enforce Destination Bucket Policy on Copy Source

> Attackers can move data across buckets without proper policy enforcement, leading to unauthorized data access and modification in RustFS.

- **Severity:** High 7.1 (`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`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 28 May 2026
- **Updated:** 28 May 2026
- **Also known as:** GHSA-wfxj-ph3v-7mjf

## What is CVE-2026-45042?

CVE-2026-45042 is a high-severity missing authorization vulnerability in rustfs, published on 28 May 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

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.

Weakness: CWE-863 (Incorrect Authorization)

## Which versions are affected by CVE-2026-45042?


## How do I fix CVE-2026-45042?

No fix has been published for CVE-2026-45042 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-45042 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-45042 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-45042 and fix it if it is affected.

What it is: CVE-2026-45042 is a high-severity missing authorization vulnerability in rustfs, published on 28 May 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-45042 exists.

Affected product: rustfs. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-45042/ (Markdown: https://insights.sbomify.com/CVE-2026-45042/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-45042
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-45042
- OSV: https://osv.dev/vulnerability/CVE-2026-45042

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-45042/
Summaries are generated and may contain mistakes; the official description above is the record.