Blocksy Companion Pro Arbitrary File Upload RCE Vulnerability
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.
Quick answer
Blocksy Companion Pro should be reviewed and updated if it matches the affected versions. The recommended fix is to apply the vendor-supported patched version or the mitigation steps below, then retest the public website with Fixnx.
Who is affected
Affected versions
- Blocksy Companion up to and including 2.1.46 with blocksy-companion-pro, WooCommerce Extra Advanced Reviews, and Custom Fonts active
Fixed versions
- Apply the latest vendor-supported patched version.
How to fix it
Blocksy Companion Pro is affected by CVE-2026-15158. Vulnerable configurations up to 2.1.46 can allow arbitrary file upload and remote code execution when the Pro, WooCommerce Extra Advanced Reviews, and Custom Fonts extensions are active. Patch or disable the risky extension path immediately.
- Inventory WordPress sites using Blocksy Companion Pro, especially sites with Blocksy Companion Pro installed.
- Update Blocksy Companion Pro beyond 2.1.46 when a vendor-fixed release is available.
- Disable Custom Fonts and WooCommerce Extra Advanced Reviews until the site is patched.
- Block uploads with double extensions such as .woff2.php or .ttf.php at the web server and WAF layer.
- Inspect uploads, custom font directories, theme directories, and plugin directories for executable files.
- Remove suspicious files and restore from trusted backups if web shell activity is detected.
- Rotate WordPress administrator, database, FTP/SFTP, and hosting credentials if compromise is suspected.
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Verify the fix
- Confirm Blocksy Companion Pro is no longer at version 2.1.46 or older on affected Pro sites.
- Attempt a safe blocked double-extension upload in staging and confirm it is rejected.
- Scan upload and font directories for executable PHP or unexpected files.
- Review web server logs for suspicious upload attempts and direct access to uploaded PHP files.
- Run a Fixnx scan and verify public WordPress exposure after cleanup.
Related categories
Trusted references
FAQ
What is affected by CVE-2026-15158?
Blocksy Companion Pro versions listed as affected should be reviewed: Blocksy Companion up to and including 2.1.46 with blocksy-companion-pro, WooCommerce Extra Advanced Reviews, and Custom Fonts active.
What should I fix first?
Start with internet-facing sites, admin panels, login flows, plugins, themes, modules, packages, and systems that process user-controlled input or sensitive data.
How do I confirm the fix worked?
Apply the patched version or mitigation, clear caches where relevant, retest the affected workflow, and run a new Fixnx scan to verify public website exposure signals.
Why can this risk appear in multiple categories?
A vulnerability can belong to more than one platform or ecosystem. Fixnx keeps one canonical risk page while also listing it in every relevant category.