Arbitrary File Upload Vulnerability in WebStack Theme for WordPress
CVE-2026-1555

9.8CRITICAL

Key Information:

Vendor

WordPress
Status
Webstack
Vendor
CVE Published:
15 April 2026

What is CVE-2026-1555?

The WebStack theme for WordPress contains a vulnerability that permits arbitrary file uploads due to insufficient file type validation in the io_img_upload() function. Any attacker, even those without authentication, can exploit this weakness to upload malicious files to the server hosting the affected site. This can lead to severe security risks, including remote code execution, if targeted files are executed by the server.

Affected Version(s)

WebStack 0 <= 1.2024

References

https://www.wordfence.com/threat-intel/vulnerabilities/id...
https://github.com/owen0o0/WebStack/blob/master/inc/ajax....
https://github.com/owen0o0/WebStack/tree/master

CVSS V3.1

Score:
9.8
Severity:
CRITICAL
Confidentiality:
High
Integrity:
High
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
None
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

Chiao-Lin Yu
.