WordPress Mailster plugin <= 4.1.17 - Arbitrary File Upload vulnerability

published 2026-07-23 3 mo ago modified 2026-10-24 16 d ago also EUVD-2026-48151

cvss: 9.1; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.5%; EPSS 0.5% chance of exploitation in 30 days, percentile 43%
public exploits: 0; none known

Editor Arbitrary File Upload in Mailster <= 4.1.17 versions.

Patch / fix

fixed in 1

EverPress Mailster 4.1.18

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: total
Assessed: 3 mo ago (2026-07-23)

Exploit prediction

0.50% chance of exploitation in the next 30 days, higher than 43% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.1	9.1	CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H

Affected products

EverPress Mailster

Classification

Weakness

CWE-434 Unrestricted Upload of File with Dangerous Type

Technology feeds

WordPress rss critical rss

References

patchstack.com /database/wordpress/plugin/mailster/vulnerability/wordpress-mailster-plugin-4-1-17-arbitrary-file-upload-vulne
vdb-entry

Sources

CVE List CVE-2026-27064
NVD CVE-2026-27064

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.

Summary