The fix, in one snippet
decode -> validate -> random server name -> object storage -> attachment downloadIllustrative values. Change the paths, hostnames and options to match your own site before using it.
The sections below explain what is tested, why it matters and the alternatives.
What we test
Scan.now inventories file input fields, actions and methods without submitting content.
Why it matters
Uploads can become stored XSS, malware delivery, parser exploits or server-side execution when active formats are trusted or served from the application origin.
How to fix it
Allow-list formats by decoded content, re-encode images, generate server-side names, limit size, scan content and serve downloads from a non-executable origin.
Where this fits
File-upload surface inventory is check 16 of 19 that the file upload surface scanner runs under page content and javascript, ordered the way they are worth fixing. That ordering is the point: Fixing this one while the check above it still fails buys less than it looks like.
Fix this one first
Above it in the same category sits Third-party scripts without Subresource Integrity (low), where scripts or stylesheets are loaded from third-party hosts without an integrity attribute. An attacker who has that does not need this, so it is the better use of the same hour.
What fixing this still leaves open
File-upload surface inventory closes one route in. Immediately below it: Inline event handlers and scripts, where the page relies on inline scripts, on* event-handler attributes or javascript: URLs; Password field autocomplete, where password fields on the page either try to disable autocomplete, which browsers ignore and password managers dislike, or lack the autocomplete tokens that let password managers fill and generate credentials safely; Third-party script inventory, where an inventory of every script the page loads from other domains.
Found in the same scan
The file upload surface scanner reports this alongside checks from other categories that are at least as serious, including Path traversal / local file inclusion, where a path-like parameter returned a known local operating-system file signature, and Session token exposed in URL, where a session-like token name appears in a discovered URL. A single run of file upload surface scanner answers all of them at once.
The first few lines
You are a senior web engineer. I ran a security and SEO scanner against my site and it reported the finding below. Fix it properly rather than suppressing the symptom.
Finding: File-upload surface inventory (info severity)
Scanner check id: file-upload-surfaceThe rest of this prompt names the pages and line numbers we found the problem on, the configuration to change, and the constraints a good answer has to respect. It is free, it just needs an account so the work is not scraped wholesale.
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