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CriticalVulnerabilityCVE-2026-111832updated 25 Oct 2026, 19:06 UTC

WP Mailster WordPress plugin lets attackers upload malicious files

Attackers can upload a hidden program (a web shell) to the website, which lets them control the site remotely. Anyone who can reach the site could potentially do this.

Official, 2 sources
SeverityCriticalCVSS 10 of 10
Being exploited?UnclearNo reports either way yet
Fix available?UnclearNo fixed version published in the sources yet
How sure is this?Official, 2 sourcesBacked by an official source

How the attack works simplified

  1. 1AttackerSends a crafted upload request
  2. 2Plugin uploadAccepts file without type checks
  3. 3Web serverStores the web shell on disk
  4. 4Remote accessAttacker runs commands via the shell
  5. ResultAttacker controls the web server

What happened

An unrestricted file upload flaw (CWE-434) in the WP Mailster WordPress plugin allows uploading web shell files to the web server.

Why it is dangerous: A web shell gives an attacker remote control of the web server, so they can steal data, change the site, or use it for further attacks. Any WordPress site running the affected plugin is at risk.

Are you affected?

You are affected if you run the WP Mailster (wp-mailster) WordPress plugin version 1.9.1.0 or earlier.

WP Mailster (wp-mailster) WordPress plugin: all versions through 1.9.1.0

What to do

  1. Check whether the WP Mailster plugin is installed and what version it is.
  2. Update WP Mailster to a version newer than 1.9.1.0 as soon as a fix is released, or check the vendor for an official mitigation.
  3. If you cannot update, disable or remove the plugin.
  4. Scan your website's upload folders for unexpected PHP or script files and review recent admin accounts.

Timeline

  1. 21 Oct 2026, 15:17 UTC
    Publicly disclosed
  2. 21 Oct 2026, 15:17 UTC
    Reported by NVD · NVD
  3. 25 Oct 2026, 19:06 UTC
    GitHub Advisory reported on it · GitHub Advisory

Sources 2 reports, oldest first

Official vendor, government CERT or advisory database

Technical details

ID
CVE-2026-111832 · GHSA-2hrr-86cg-w5v9
CVSS
10 / 10
EPSS
0.4% chance of exploitation within 30 days
Disclosed
21 Oct 2026, 15:17 UTC
On Zero Radar
before the radar started
Last change
25 Oct 2026, 19:06 UTC

The plain-language parts and the attack diagram were written by an AI model (anthropic/claude-haiku-5.5) from the sources above. Facts like versions, exploitation and dates come from the sources themselves. How Zero Radar works

WP Mailster WordPress plugin lets attackers upload malicious files · Zero Radar