CVE-2026-27064Network attack vector

Editor-level arbitrary file upload

Published Jul 23, 2026 · Updated Jul 23, 2026

Arbitrary file upload in EverPress Mailster 4.1.17 and earlier allows remote authenticated users with Editor access to upload dangerous files. Patchstack does not identify the affected upload handler or disclose which filename, extension, MIME-type, or content validation accepts the files. Editor-level access is required, and uploaded executable files can provide further access to the WordPress site.

CVSS severity9.1
Critical
EPSS probability0.50%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Arbitrary file upload in EverPress Mailster 4.1.17 and earlier allows remote authenticated users with Editor access to upload dangerous files. Patchstack does not identify the affected upload handler or disclose which filename, extension, MIME-type, or content validation accepts the files. Editor-level access is required, and uploaded executable files can provide further access to the WordPress site.

The record

CVE
CVE-2026-27064
Published
Jul 23, 2026
Updated
Jul 23, 2026
Vendor
EverPress
Product
Mailster
Classifications
CWE-434, T1505.003
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jul 23, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 23, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=n/a <=4.1.17 changes=[{"at":"4.1.18","status":"unaffected"}]

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

EverPress · Mailsterversion=n/a <=4.1.17 changes=[{"at":"4.1.18","status":"unaffected"}]

Published CVSS scores

9.1PatchstackCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-434Unrestricted Upload of File with Dangerous Type
T1505.003Server Software Component: Web Shell

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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