# CVE-2026-6378: Maxi Blocks <= 2.1.9 - Authenticated (Author+) Stored Cross-Site Scripting via Style Card REST API

> Authenticated attackers with Author access can inject scripts via the Style Card REST API, executing code in admin panels and user sessions.

- **Severity:** Medium 6.4 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A: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:** 2 May 2026
- **Updated:** 4 May 2026
- **Also known as:** GHSA-8p3w-9597-pwh9

## What is CVE-2026-6378?

CVE-2026-6378 is a medium-severity cross-site scripting vulnerability in ckp267 MaxiBlocks Builder | 17,000+ Design Assets, Patterns, Icons & Starter Sites, published on 2 May 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

The Maxi Blocks plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the `/wp-json/maxi-blocks/v1.0/style-card` REST API endpoint in all versions up to, and including, 2.1.9 due to insufficient input sanitization and output escaping of the `sc_styles` parameter. This makes it possible for authenticated attackers, with Author-level access and above, to inject arbitrary web scripts that execute on every page where the plugin's style card styles are loaded, including across the entire WordPress admin panel.

Weakness: CWE-79 (Improper Neutralization of Input During Web Page Generation)

## Which versions are affected by CVE-2026-6378?


## How do I fix CVE-2026-6378?

No fix has been published for CVE-2026-6378 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-6378 being exploited?

There is no known exploitation of CVE-2026-6378 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-6378 and fix it if it is affected.

What it is: CVE-2026-6378 is a medium-severity cross-site scripting vulnerability in ckp267 MaxiBlocks Builder | 17,000+ Design Assets, Patterns, Icons & Starter Sites, published on 2 May 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-6378 in the wild and no public exploit code.

Affected product: ckp267 MaxiBlocks Builder | 17,000+ Design Assets, Patterns, Icons & Starter Sites. 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-2026-6378/ (Markdown: https://insights.sbomify.com/CVE-2026-6378/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-6378
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-6378
- OSV: https://osv.dev/vulnerability/CVE-2026-6378

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-6378/
Summaries are generated and may contain mistakes; the official description above is the record.