# CVE-2026-54583: mport package bundle downloads allow unsafe destination filenames

> Attackers can write package data to arbitrary locations via malicious index data due to missing filename validation in MidnightBSD's mport.

- **Severity:** High 8.3 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:L/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 17 Sep 2026
- **Updated:** 17 Sep 2026
- **Also known as:** GHSA-mr62-mqwj-vhh3

## What is CVE-2026-54583?

CVE-2026-54583 is a high-severity path traversal vulnerability in MidnightBSD mport, published on 17 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

mport is the MidnightBSD Package Manager. Prior to 2.7.8, libmport/fetch.c did not consistently reject empty, dot, dot-dot, or slash-containing bundle filenames before composing package download and write paths. Malicious package index data could place an unsafe value in indexEntry->bundlefile, and the missing is_valid_bundle_filename() checks allowed downloaded package data to be written outside the intended cache location or to an unsafe destination name. This issue is fixed in version 2.7.8.

Weakness: CWE-73 (External Control of File Name or Path), CWE-22 (Improper Limitation of a Pathname to a Restricted Directory)

## Which versions are affected by CVE-2026-54583?


## How do I fix CVE-2026-54583?

No fix has been published for CVE-2026-54583 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-54583 being exploited?

There is no known exploitation of CVE-2026-54583 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-54583 and fix it if it is affected.

What it is: CVE-2026-54583 is a high-severity path traversal vulnerability in MidnightBSD mport, published on 17 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-54583 in the wild and no public exploit code.

Affected product: MidnightBSD mport. 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-2026-54583/ (Markdown: https://insights.sbomify.com/CVE-2026-54583/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-54583
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-54583
- OSV: https://osv.dev/vulnerability/CVE-2026-54583

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-54583/
Summaries are generated and may contain mistakes; the official description above is the record.