CVE-2026-111832: WP Mailster arbitrary file upload vulnerability
critical 10.0 published 2026-10-21
- Affected versions
- 1.9.1.0 and older
- Fixed in
- 1.9.2.0
- Latest version
- 1.9.2.0
- Severity
- Critical · CVSS 10.0
- Active installs
- 300+
- Type
- Arbitrary file upload
What an attacker needs
- Access: None. No account or login is needed (per the CVSS score).
CVSS vector (score by Patchstack): CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
What to do now
- Update WP Mailster to 1.9.2.0 or newer: Dashboard → Updates, or Plugins → “update now”.
- If you cannot update right away, deactivate it until you can.
- Turn on auto-updates for it: Plugins → “Enable auto-updates” on its row.
- Not sure which version you run? Check your version against every known WP Mailster issue.
With WP-CLI:
wp plugin get wp-mailster --field=version. - If you ran an affected version and something looks off (new admin users, spam pages, redirects), run the free scan below.
The advisory
Unrestricted Upload of File with Dangerous Type vulnerability in WP Mailster WP Mailster wp-mailster allows Upload a Web Shell to a Web Server.This issue affects WP Mailster: from n/a through 1.9.1.0.
References
- NVD CVE-2026-111832 nvd.nist.gov
- Patchstack advisory patchstack.com
Related
Ran an affected version? Check your site for signs of a hack
The free scan reads the public side of your site and looks for spam pages, hidden redirects, injected scripts and blacklist entries. No login, no install, about a minute.
Where this data comes from
- CVE record, score and references: NIST National Vulnerability Database (NVD), checked 2026-11-04. This product uses data from the NVD API but is not endorsed or certified by the NVD.
- Versions and install counts: wordpress.org/plugins/wp-mailster (Plugins API), fetched 2026-11-04.
- The summary, “what an attacker needs” and “what to do” sections are our plain-English reading of the record and the plugin's release history; the quoted description is the record's own text. Spot an error? Email Daniel.