CVE-2026-3335: The Canto plugin for WordPress is vulnerable to Missing Authorization in all versions up to, and including, 3.1.1 via the `/wp-content/plugins/canto/i...

Description

The Canto plugin for WordPress is vulnerable to Missing Authorization in all versions up to, and including, 3.1.1 via the `/wp-content/plugins/canto/includes/lib/copy-media.php` file. This is due to the file being directly accessible without any authentication, authorization, or nonce checks, and the `fbc_flight_domain` and `fbc_app_api` URL components being accepted as user-supplied POST parameters rather than read from admin-configured options. Since the attacker controls both the destination server and the `fbc_app_token` value, the entire fetch-and-upload chain is attacker-controlled — the server never contacts Canto's legitimate API, and the uploaded file originates entirely from the attacker's infrastructure. This makes it possible for unauthenticated attackers to upload arbitrary files (constrained to WordPress-allowed MIME types) to the WordPress uploads directory. Additional endpoints (`detail.php`, `download.php`, `get.php`, `tree.php`) are also directly accessible without authentication and make requests using a user-supplied `app_api` parameter combined with an admin-configured subdomain.

Metrics

CVSS 3.1

5.3/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

EPSS Probability

0.44%

34.9th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-862

References

Timeline

Published: Mar 21, 2026
Last Modified: Jun 17, 2026
Status: Deferred

Frequently Asked Questions

What is CVE-2026-3335?

The Canto plugin for WordPress is vulnerable to Missing Authorization in all versions up to, and including, 3.1.1 via the `/wp-content/plugins/canto/includes/lib/copy-media.php` file. This is due to the file being directly accessible without any authentication, authorization, or nonce checks, and the `fbc_flight_domain` and `fbc_app_api` URL components being accepted as user-supplied POST parameters rather than read from admin-configured options. Since the attacker controls both the destination server and the `fbc_app_token` value, the entire fetch-and-upload chain is attacker-controlled — the server never contacts Canto's legitimate API, and the uploaded file originates entirely from the attacker's infrastructure. This makes it possible for unauthenticated attackers to upload arbitrary files (constrained to WordPress-allowed MIME types) to the WordPress uploads directory. Additional endpoints (`detail.php`, `download.php`, `get.php`, `tree.php`) are also directly accessible without authentication and make requests using a user-supplied `app_api` parameter combined with an admin-configured subdomain.

How severe is CVE-2026-3335?

CVE-2026-3335 has a CVSS score of 5.3/10 (MEDIUM severity). The EPSS model estimates a 0.44% probability of exploitation in the next 30 days.

How do I fix CVE-2026-3335?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.