CVE-2026-109983

YMC Filter <= 3.12.19 - Authenticated (Author+) Stored DOM-Based Cross-Site Scripting via 'post_title' Parameter

2026-10-16 19:36
Wordfence PRISM

Strategic Overview

Status
Patched in 3.12.20
Affected Plugin
YMC Filter
Affected Version
<= 3.12.19
CVSS
6.4Medium
Weakness type
CWE-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CVE
CVE-2026-109983
View all YMC Filter vulnerabilities

At a glance

CVE-2026-109983 is a medium-severity Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in the YMC Filter WordPress plugin, affecting versions <= 3.12.19. It carries a CVSS score of 6.4 (reachable over the network; low attack complexity). Exploitation requires an authenticated account at Author level or above. The issue is fixed in version 3.12.20; sites on affected versions should update now. Disclosed October 2026, reported by Wordfence PRISM.

Vulnerability Overview

The YMC Filter plugin for WordPress is vulnerable to Stored DOM-Based Cross-Site Scripting via the 'post_title' parameter in all versions up to, and including, 3.12.19 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with author-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. The autocomplete REST endpoint is registered with a permission callback that unconditionally returns true, meaning any site visitor — including unauthenticated users — can trigger the payload simply by typing in the YMC filter search box, while only Author-level access is required to store it.

Technical Analysis

The vector marks this flaw as remotely reachable over the network, with low attack complexity — no special timing or configuration is needed, and no interaction from a victim user.

CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

YMC Filter <= 3.12.19 carries this weakness at post_title, and reaching it takes an account at Author level or above. Cross-site scripting happens when input from a request is written into a page without being escaped for the context it lands in, so the browser parses attacker-supplied text as markup or script.

Injected script runs with the privileges of whoever views the affected page, which is how these flaws turn into administrator session theft, silent account creation or persistent backdoors in page content. For YMC Filter the fix is 3.12.20: builds <= 3.12.19 are affected, anything from 3.12.20 onward is not.

Remediation

Update to version 3.12.20, or a newer patched version

How does WordSec protect against this?

An attacker needs Author access first, so the firewall sees the attempt as traffic from a logged-in account: WordSec's web application firewall inspects request payloads before WordPress loads them. None of that substitutes for the fix: YMC Filter 3.12.20 closes this, and updating the plugin is the step that ends it.

  • Firewall
  • Alerts

External References

https://www.cve.org/CVERecord?id=CVE-2026-109983https://www.wordfence.com/threat-intel/vulnerabilities/id/27cfa62d-ba16-4344-be0c-82cac4d21d1chttps://nvd.nist.gov/vuln/detail/CVE-2026-109983

Related records

Vulnerability data © Defiant, Inc., provided under the Wordfence Intelligence T&C