# CVE-2026-15420: Path traversal in Nexter Blocks – Gutenberg Blocks, Page Builder & AI Website Builder

> Authenticated subscribers can delete arbitrary CSS/JS files via path traversal, causing denial of service or asset destruction in Nexter Blocks.

- **Severity:** Medium 4.3 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/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:** 24 Jul 2026
- **Updated:** 24 Jul 2026
- **Also known as:** GHSA-cg9r-cc95-vm62

## What is CVE-2026-15420?

CVE-2026-15420 is a medium-severity path traversal vulnerability in posimyththemes Nexter Blocks – Gutenberg Blocks, Page Builder & AI Website Builder, published on 24 Jul 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

The Nexter Blocks – Gutenberg Blocks, Page Builder & AI Website Builder plugin for WordPress is vulnerable to Directory Traversal in all versions up to, and including, 5.0.0 via the 'plus_name' parameter. This makes it possible for authenticated attackers, with subscriber-level access and above, to delete arbitrary JS/CSS files on the server, which can lead to denial of service or destruction of critical plugin and theme assets.

Weakness: CWE-22 (Improper Limitation of a Pathname to a Restricted Directory)

## Which versions are affected by CVE-2026-15420?


## How do I fix CVE-2026-15420?

No fix has been published for CVE-2026-15420 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-15420 being exploited?

There is no known exploitation of CVE-2026-15420 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-15420 and fix it if it is affected.

What it is: CVE-2026-15420 is a medium-severity path traversal vulnerability in posimyththemes Nexter Blocks – Gutenberg Blocks, Page Builder & AI Website Builder, published on 24 Jul 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-2026-15420 in the wild and no public exploit code.

Affected product: posimyththemes Nexter Blocks – Gutenberg Blocks, Page Builder & AI Website Builder. 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-2026-15420/ (Markdown: https://insights.sbomify.com/CVE-2026-15420/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-15420
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-15420
- OSV: https://osv.dev/vulnerability/CVE-2026-15420

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-15420/
Summaries are generated and may contain mistakes; the official description above is the record.