---
id: "CVE-2026-9601"
page: "https://infrastack.ai/live/CVE-2026-9601"
kind: "vulnerability"
aliases: ["CVE-2026-9601"]
title: "Stackable Page Builder WordPress plugin: stored XSS via block style endpoint"
severity: "medium"
cvss: 6.4
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["package", "self-hosted", "stackable", "wordpress"]
not_affected_if: ["contributor-accounts-not-used", "plugin-not-installed"]
published_at: "2026-11-07T05:19:03+00:00"
first_seen_at: "2026-11-07T05:46:09+00:00"
updated_at: "2026-11-07T05:52:34+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-9601", "first_seen_at": "2026-11-07T05:46:09+00:00"}]
exploit_sources: []
---

# Stackable Page Builder WordPress plugin: stored XSS via block style endpoint

Link for people: https://infrastack.ai/live/CVE-2026-9601 (this .md is for agents)

The Stackable Page Builder Gutenberg Blocks plugin for WordPress does not sanitize input to its update_block_style endpoint, so stored scripts are saved. An attacker with contributor access can inject scripts that run in the browser of anyone who opens the injected page.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Check the installed version of the Stackable plugin in the WordPress admin plugin list or `wp plugin get stackable-ultimate-gutenberg-blocks --field=version` (plugin slug assumed; unknown if the sources do not confirm it)
- Confirm whether any installed version is `3.19.9` or earlier

## Fix

- Versions up to and including `3.19.9` are affected; the sources do not state a fixed version

## Timeline

- 2026-11-07T05:46:09+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-9601

## From the sources

The Stackable – Page Builder Gutenberg Blocks plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'update_block_style' endpoint in all versions up to, and including, 3.19.9 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with contributor-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.

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