# CVE-2019-9842: File upload in n/a

> Remote attackers can execute arbitrary code by uploading malicious files via the blog post handler due to missing file extension validation.

- **Severity:** High 7.2 (`CVSS:3.0/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 14 Jun 2019
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-q26p-9rm7-92f4

## What is CVE-2019-9842?

CVE-2019-9842 is a high-severity vulnerability in n/a, published on 14 Jun 2019. An attacker needs administrator access to exploit it, with no action from the victim.

### Official description

madskristensen MiniBlog through 2018-05-18 allows remote attackers to execute arbitrary ASPX code via an IMG element with a data: URL, because SaveFilesToDisk in app_code/handlers/PostHandler.cs writes a decoded base64 string to a file without validating the extension.

Weakness: CWE-434 (Unrestricted Upload of File with Dangerous Type)

## Which versions are affected by CVE-2019-9842?

It affects 1 product.


Products: Miniblog Project Miniblog.

## How do I fix CVE-2019-9842?

No fix has been published for CVE-2019-9842 yet. Limit exposure of the affected software until one is available.

## Is CVE-2019-9842 being exploited?

There is no known exploitation of CVE-2019-9842 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2019-9842 and fix it if it is affected.

What it is: CVE-2019-9842 is a high-severity vulnerability in n/a, published on 14 Jun 2019. An attacker needs administrator access to exploit it, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2019-9842 in the wild and no public exploit code.

Affected product: n/a. 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-2019-9842/ (Markdown: https://insights.sbomify.com/CVE-2019-9842/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2019-9842
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2019-9842
- OSV: https://osv.dev/vulnerability/CVE-2019-9842

---
From sbomify Insights: https://insights.sbomify.com/CVE-2019-9842/
Summaries are generated and may contain mistakes; the official description above is the record.