# CVE-2023-53933: Serendipity 2.4.0 Authenticated Remote Code Execution via File Upload

> Authenticated attackers can upload malicious PHP files to execute arbitrary commands on the server.

- **Severity:** High 8.7 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/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:** 17 Dec 2025
- **Updated:** 7 Apr 2026
- **Also known as:** GHSA-87vx-4xf9-32hg

## What is CVE-2023-53933?

CVE-2023-53933 is a high-severity vulnerability in S9y Serendipity, published on 17 Dec 2025. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

Serendipity 2.4.0 contains a remote code execution vulnerability that allows authenticated attackers to upload malicious PHP files with .phar extension. Attackers can upload files with system command payloads to the media upload endpoint and execute arbitrary commands on the server.

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

## Which versions are affected by CVE-2023-53933?

It affects 1 product.


Products: S9y Serendipity.

## How do I fix CVE-2023-53933?

No fix has been published for CVE-2023-53933 yet. Limit exposure of the affected software until one is available.

## Is CVE-2023-53933 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2023-53933 exists.

## Other vulnerabilities in S9y Serendipity

- [CVE-2005-1449](https://insights.sbomify.com/CVE-2005-1449/): Other in n/a (critical 10.0)
- [CVE-2005-1452](https://insights.sbomify.com/CVE-2005-1452/): Missing authorization in n/a (critical 10.0)
- [CVE-2020-10964](https://insights.sbomify.com/CVE-2020-10964/): File upload in n/a (critical 9.8)
- [CVE-2011-1134](https://insights.sbomify.com/CVE-2011-1134/): Cross-site scripting in n/a (critical 9.8)
- [CVE-2016-10752](https://insights.sbomify.com/CVE-2016-10752/): File upload in n/a (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-53933 and fix it if it is affected.

What it is: CVE-2023-53933 is a high-severity vulnerability in S9y Serendipity, published on 17 Dec 2025. 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-2023-53933 exists.

Affected product: S9y Serendipity. 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-2023-53933/ (Markdown: https://insights.sbomify.com/CVE-2023-53933/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-53933
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-53933
- OSV: https://osv.dev/vulnerability/CVE-2023-53933

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-53933/
Summaries are generated and may contain mistakes; the official description above is the record.