---
id: "CVE-2026-111830"
kind: "vulnerability"
aliases: ["CVE-2026-111830"]
title: "WP Mailster: stored XSS through 1.9.1.0 lets injected scripts run"
severity: "high"
cvss: 7.1
epss: 0.00146
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["package", "self-hosted", "wordpress", "wp-mailster"]
not_affected_if: ["plugin-not-installed"]
published_at: "2026-10-22T09:17:13+00:00"
first_seen_at: "2026-10-23T21:57:30+00:00"
updated_at: "2026-10-25T03:31:41+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-111830", "first_seen_at": "2026-10-23T21:57:30+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2026-111830", "first_seen_at": "2026-10-24T07:15:52+00:00"}]
---

# WP Mailster: stored XSS through 1.9.1.0 lets injected scripts run

WP Mailster, a WordPress newsletter plugin, does not neutralize input on some pages, so stored cross-site scripting is possible. An attacker who can store content in the plugin can run scripts in the browser of a logged-in user who views it.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Check the installed WP Mailster plugin version in the WordPress admin under Plugins, or with `wp plugin get wp-mailster --field=version`
- Compare the result against 1.9.1.0; versions up to and including 1.9.1.0 are listed as affected

## Fix

- Update WP Mailster to a version later than `1.9.1.0` once the vendor publishes a fixed release; the sources do not name the fixed version
- Until then, restrict which roles can add subscribers or edit campaign content

## Timeline

- 2026-10-23T21:57:30+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-111830
- 2026-10-24T07:15:52+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2026-111830

## From the sources

Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in WP Mailster WP Mailster wp-mailster allows Stored XSS.This issue affects WP Mailster: from n/a through 1.9.1.0.

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_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_