# 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.

- **Severity:** Medium 5.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 21 Mar 2026
- **Updated:** 8 Apr 2026
- **Also known as:** GHSA-j9m2-xx67-38fc

## 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 (Missing Authorization)

## 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.

## 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:

- Canto <= 3.1.1 - Missing Authorization to Unauthenticated File Upload (nuclei): http/cves/2026/CVE-2026-3335.yaml

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-3335 and fix it if it is affected.

What it is: 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.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-3335 exists.

Affected product: flightbycanto Canto. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-3335/ (Markdown: https://insights.sbomify.com/CVE-2026-3335/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-3335
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-3335
- OSV: https://osv.dev/vulnerability/CVE-2026-3335

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-3335/
Summaries are generated and may contain mistakes; the official description above is the record.