# CVE-2023-40555: WordPress Flatsome Theme <= 3.17.5 is vulnerable to PHP Object Injection

> An attacker can exploit PHP object injection in the Flatsome WordPress theme to potentially execute arbitrary code on the server.

- **Severity:** High 8.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 20 Dec 2023
- **Updated:** 28 Apr 2026
- **Also known as:** GHSA-9fmf-6xvc-qw23

## What is CVE-2023-40555?

CVE-2023-40555 is a high-severity unsafe deserialization vulnerability in UX-themes Flatsome | Multi-Purpose Responsive WooCommerce Theme, published on 20 Dec 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Deserialization of Untrusted Data vulnerability in UX-themes Flatsome | Multi-Purpose Responsive WooCommerce Theme.This issue affects Flatsome | Multi-Purpose Responsive WooCommerce Theme: from n/a through 3.17.5.

Weakness: CWE-502 (Deserialization of Untrusted Data)

## Which versions are affected by CVE-2023-40555?

It affects 1 product.


Products: Uxthemes Flatsome.

## How do I fix CVE-2023-40555?

No fix has been published for CVE-2023-40555 yet. Limit exposure of the affected software until one is available.

## Is CVE-2023-40555 being exploited?

There is no known exploitation of CVE-2023-40555 in the wild and no public exploit code.

## Other vulnerabilities in UX-themes Flatsome | Multi-Purpose Responsive WooCommerce Theme

- [CVE-2023-28994](https://insights.sbomify.com/CVE-2023-28994/): WordPress Flatsome Theme <= 3.16.8 is vulnerable to Cross Site Scripting (XSS) (high 7.1)
- [CVE-2024-5346](https://insights.sbomify.com/CVE-2024-5346/): Cross-site scripting in Flatsome (medium 6.4)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-40555 and fix it if it is affected.

What it is: CVE-2023-40555 is a high-severity unsafe deserialization vulnerability in UX-themes Flatsome | Multi-Purpose Responsive WooCommerce Theme, published on 20 Dec 2023. 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-2023-40555 in the wild and no public exploit code.

Affected product: UX-themes Flatsome | Multi-Purpose Responsive WooCommerce Theme. 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-2023-40555/ (Markdown: https://insights.sbomify.com/CVE-2023-40555/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-40555
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-40555
- OSV: https://osv.dev/vulnerability/CVE-2023-40555

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-40555/
Summaries are generated and may contain mistakes; the official description above is the record.