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PatchSiren cyber security CVE debrief

CVE-2026-16558 YMC Filter CVE debrief

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. This vulnerability, with a CVSS score of 5.4, poses a medium risk of stored cross-site scripting (XSS) attacks. Administrators should verify affected systems, apply security patches, and monitor for suspicious activity related to the Contributor role and above. Evidence is based on official CVE Program and NVD records, as well as a source reference from WPScan, providing details on the vulnerability and its potential impact.

Vendor
YMC Filter
Product
YMC Filter WordPress plugin
CVSS
MEDIUM 5.4
CISA KEV
Not listed in stored evidence
Original CVE published
2026-08-08
Original CVE updated
2026-08-26
Advisory published
2026-08-08
Advisory updated
2026-08-26

Who should care

Administrators of WordPress sites using the YMC Filter plugin, security teams monitoring for potential XSS attacks, and users with the Contributor role and above in affected systems should be aware of this vulnerability and take necessary defensive actions.

Technical summary

The YMC Filter WordPress plugin before 3.12.8 is vulnerable to stored cross-site scripting (XSS) attacks. An attacker with the Contributor role and above can store malicious JavaScript code in a layout builder setting, which can be executed in the browser of any visitor viewing an affected filter. The plugin does not properly sanitize and escape the layout builder setting, and does not verify object ownership when the setting is saved.

Defensive priority

Medium-priority defensive actions are recommended due to the medium CVSS score of 5.4 for this vulnerability.

Recommended defensive actions

  • Inventory and verify affected systems for the YMC Filter WordPress plugin version.
  • Apply the latest security patch for the YMC Filter WordPress plugin.
  • Monitor for suspicious activity related to the Contributor role and above.
  • Restrict access to the layout builder setting to authorized users only.
  • Implement additional security measures to prevent JavaScript injection attacks.

Evidence notes

Evidence is based on official CVE Program and NVD records, as well as a source reference from WPScan. The CVE description provides details on the vulnerability, including the affected plugin and the potential impact.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-16558 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-16558

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-16558 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-16558

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.