nathank
June 10, 2026, 3:14am
1
Currently, I’m finding that clicking on the PDF link when a PDF preview is active currently attempts to download the PDF (undesired) instead of opening it in a new tab.
This is with simple self-hosting (single container, no CDN, no S3, horizon theme).
This whole thing was addressed back here:
The reason why this is a problem is that a common user desire is to read an inline PDF in the entire window, as the iframe is quite restrictive. Download adds an unecessarily annoying step. And there is already a download button in the toolbar of the PDF viewer in the iframe (at least there is in Chrome).
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We were being inconsistent with the display type depending on whether you were using S3 or not. That should be fixed by
main ← fix-inline-safe-uploads-local-store
approved 05:17PM - 14 Jul 26 UTC
Inline-safe uploads (images, PDFs, audio and video) served from the local
file s… tore were sent with `Content-Disposition: attachment`, so clicking a
PDF link downloaded the file instead of opening it in the browser. This was
inconsistent with the S3 store, which already serves these files inline, and
it left simple self-hosted (single-container, no S3/CDN) sites unable to open
PDFs inline.
`UploadsController#send_file_local_upload` only set the disposition to
`attachment` for unsafe types, and to `inline` when `?inline=1` was passed,
leaving it unset otherwise. Rails' `send_file` defaults an unset disposition
to `attachment`, so inline-safe files fell through to a download.
Inline-safe files are now served with `Content-Disposition: inline` by
default, mirroring the S3 store, while unsafe types (HTML, SVG, XML, ...) and
explicit downloads (`?dl=1`) keep the `attachment` disposition. The redundant
`params[:inline]` branch is removed, since inline-safe files are now inline by
default.
The `Content-Security-Policy: sandbox;` header stays on **every** response as
defense-in-depth: if the `is_inline_safe?` allowlist is ever wrong, the
sandbox forces an opaque origin and disables script execution so a
misclassified file cannot run as a document in our origin. It does not
interfere with inline viewing — `sandbox` sandboxes scripts *inside* the
served file, not the browser's native rendering of it. Chrome's built-in PDF
viewer and Firefox's pdf.js both render sandboxed PDFs identically to
unsandboxed ones, and images/audio/video decode natively regardless.
A spec locks the allowlist invariant by asserting no inline-safe extension
maps to a script-capable content type, so re-adding something like SVG or XML
to the allowlist fails CI instead of becoming a stored XSS.
(cc @david )
The fact that clicking on a file opens automatically in another tab is more a product
3 Likes