# CVE-2026-16618: ImproveSEO <= 2.0.11 - Unauthenticated Arbitrary File Upload Leading to Remote Code Execution

> Unauthenticated attackers can upload malicious PHP files to achieve remote code execution on sites using the Improve SEO plugin.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 4 Aug 2026
- **Updated:** 4 Aug 2026
- **Also known as:** GHSA-62v2-7mcm-qpm4

## What is CVE-2026-16618?

CVE-2026-16618 is a critical vulnerability in Unknown Improve SEO, published on 4 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

The Improve SEO WordPress plugin through 2.0.11 does not properly validate uploaded files, checking only the file content type while writing the file with the attacker-supplied extension into a publicly accessible directory, allowing unauthenticated users to upload executable PHP files and achieve remote code execution.

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

## Which versions are affected by CVE-2026-16618?


## How do I fix CVE-2026-16618?

No fix has been published for CVE-2026-16618 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-16618 being exploited?

There is no known exploitation of CVE-2026-16618 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-16618 and fix it if it is affected.

What it is: CVE-2026-16618 is a critical vulnerability in Unknown Improve SEO, published on 4 Aug 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-2026-16618 in the wild and no public exploit code.

Affected product: Unknown Improve SEO. 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-2026-16618/ (Markdown: https://insights.sbomify.com/CVE-2026-16618/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-16618
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-16618
- OSV: https://osv.dev/vulnerability/CVE-2026-16618

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-16618/
Summaries are generated and may contain mistakes; the official description above is the record.