CVE-2026-15158

Blocksy Companion <= 2.1.46 - Unauthenticated Arbitrary File Upload via 'blc-review-images[]' Parameter

2026-07-01 13:28
Nguyen Ba Khanh

Strategic Overview

Status
Patched in 2.1.47
Affected Plugin
Blocksy Companion
Affected Version
<= 2.1.46
CVSS
9.8Critical
Weakness type
CWE-434 · Unrestricted Upload of File with Dangerous Type
CVE
CVE-2026-15158
View all Blocksy Companion vulnerabilities

At a glance

CVE-2026-15158 is a critical-severity Unrestricted Upload of File with Dangerous Type vulnerability in the Blocksy Companion WordPress plugin, affecting versions <= 2.1.46. It carries a CVSS score of 9.8 (reachable over the network; low attack complexity; high confidentiality, integrity, availability impact). Exploitation requires no authentication. The issue is fixed in version 2.1.47; sites on affected versions should update now. Disclosed July 2026, reported by Nguyen Ba Khanh.

Vulnerability Overview

The Blocksy Companion plugin for WordPress is vulnerable to Arbitrary File Upload in all versions up to, and including, 2.1.46 via the save_attachments function. This is due to the Custom Fonts extension registering a wp_check_filetype_and_ext filter that approves any filename containing .woff2 or .ttf as a substring via strpos() rather than validating that those strings appear as the final extension via PATHINFO_EXTENSION — allowing double-extension filenames such as shell.woff2.php to pass MIME validation and be handled as permitted font files. This makes it possible for unauthenticated attackers to upload files that may be executable, which makes remote code execution possible. This vulnerability is only exploitable when the premium version of the plugin (blocksy-companion-pro) is installed with both the WooCommerce Extra (Advanced Reviews) and Custom Fonts extensions active; the free blocksy-companion plugin does not contain the vulnerable code paths. CVE-2026-58480 is a duplicate of this CVE.

Technical Analysis

The vector marks this flaw as remotely reachable over the network, with low attack complexity — no special timing or configuration is needed, and no privileges on the target site, and no interaction from a victim user. A successful exploit has high impact on confidentiality, integrity, availability — full site compromise territory.

CWE-434: Unrestricted Upload of File with Dangerous Type

Blocksy Companion <= 2.1.46 carries this weakness at strpos(), and reaching it takes no account at all. An unrestricted file upload lets a caller store a file whose type or destination the application does not properly constrain.

If an uploaded file lands anywhere the server will execute, the flaw becomes remote code execution and the site should be treated as fully compromised. For Blocksy Companion the fix is 2.1.47: builds <= 2.1.46 are affected, anything from 2.1.47 onward is not.

Remediation

Update to version 2.1.47, or a newer patched version

How does WordSec protect against this?

Requests carrying this pattern arrive without a session, so nothing upstream of the firewall gets a chance to reject them: WordSec's web application firewall inspects request payloads before WordPress loads them. Classes like this one can leave something behind, so the staged malware scanner is the second half: it looks for dropped files and modified code rather than for the request that created them. None of that substitutes for the fix: Blocksy Companion 2.1.47 closes this, and updating the plugin is the step that ends it.

  • Firewall
  • Scanner
  • Login Security

External References

https://www.cve.org/CVERecord?id=CVE-2026-15158https://www.wordfence.com/threat-intel/vulnerabilities/id/2df449b4-3f3b-4afc-b391-8d8d11710c07https://nvd.nist.gov/vuln/detail/CVE-2026-15158

Related records

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