# CVE-2026-109983: YMC Filter <= 3.12.19 - Authenticated (Author+) Stored DOM-Based Cross-Site Scripting via 'post_title' Parameter

> Authenticated attackers can inject scripts via post titles that execute for all users, including unauthenticated visitors, due to insufficient sanitization.

- **Severity:** Medium 6.4 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 17 Oct 2026
- **Updated:** 18 Oct 2026
- **Also known as:** GHSA-r26w-hjm4-pvpr

## What is CVE-2026-109983?

CVE-2026-109983 is a medium-severity cross-site scripting vulnerability in wssoffice21 YMC Filter, published on 17 Oct 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

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.

Weakness: CWE-79 (Improper Neutralization of Input During Web Page Generation)

## Which versions are affected by CVE-2026-109983?


## How do I fix CVE-2026-109983?

No fix has been published for CVE-2026-109983 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-109983 being exploited?

There is no known exploitation of CVE-2026-109983 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-109983 and fix it if it is affected.

What it is: CVE-2026-109983 is a medium-severity cross-site scripting vulnerability in wssoffice21 YMC Filter, published on 17 Oct 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-109983 in the wild and no public exploit code.

Affected product: wssoffice21 YMC Filter. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-109983/ (Markdown: https://insights.sbomify.com/CVE-2026-109983/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-109983
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-109983
- OSV: https://osv.dev/vulnerability/CVE-2026-109983

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-109983/
Summaries are generated and may contain mistakes; the official description above is the record.