Arbitrary file upload in Owen Webstack

CVE-2026-1555

The WebStack theme for WordPress is vulnerable to arbitrary file uploads due to missing file type validation in the io_img_upload() function in all versions up to, and including, 1.2024. This makes it possible for unauthenticated attackers to upload arbitrary files on the affected site's server which may make remote code execution possible.

Vulnerability class: Unrestricted File Upload

Published · last modified .

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.010 (60.8th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 61st percentile — 60.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-1555: held from 0.010 to 0.010.

EPSS over last 30 days · oldest: 0.010 · newest: 0.010 · change: 0.000

Affected products

Weakness classification (CWE)

Public proof-of-concept exploits

References

Frequently asked questions

What is CVE-2026-1555?
CVE-2026-1555 is a critical-severity vulnerability in Owen Webstack, classified under Unrestricted Upload of File with Dangerous Type. CVSS score: 9.8/10. Published 2026-04-15.
How severe is CVE-2026-1555?
Critical severity. CVSS v3 base score is 9.8 out of 10.
Is CVE-2026-1555 known to be exploited?
4 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.