CVE-2026-3335 Canto <= 3.1.1 - Missing Authorization to Unauthenticated File Upload
Unauthenticated attackers can upload arbitrary files to the WordPress uploads directory due to missing authorization checks in the Canto plugin.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-3335?
CVE-2026-3335 is a medium-severity missing authorization vulnerability in flightbycanto Canto, published on 21 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Weakness: CWE-862
Which versions are affected by CVE-2026-3335?
How do I fix CVE-2026-3335?
No fix has been published for CVE-2026-3335 yet. Limit exposure of the affected software until one is available.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2026-3335 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-3335 exists.
Public exploit code: 1 Nuclei template.
Sources
Also known as GHSA-j9m2-xx67-38fc.