CVE-2026-72697: Grav: media_directory() Twig function allows filesystem path traversal and file content disclosure from sandboxed page content

The media_directory() Twig function is allow-listed for use in sandboxed, editor-authored page content (system/config/security.yaml). Its implementation, GravExtension::mediaDirFunc(), only treats the input as unsafe when it looks like a Grav stream (user://, theme://, etc). If the input is instead a plain filesystem path, absolute or relative, the stream check is skipped entirely and the raw string is handed straight to new Media($media_dir), which lists every file in that directory whose extension matches a configured media type (which by default includes txt, json, xml, pdf, doc, docx, and more, not just images) and builds Medium objects for them.

Separately, the sandbox’s own allow-list for the Medium class includes the filepath accessor. A code comment directly above that allow-list entry states the developers’ intent was for filepath to be part of the “dangerous surface” that “stays blocked”, but it is listed as an allowed method on the very same line, contradicting that stated intent.

Combined, a user who can enter page content that gets processed as Twig (process.twig: true in frontmatter, or any modular page, which is unsandboxed and unconditional per the code comment in processPage()) can point media_directory() at any directory the web server process can read, anywhere on the filesystem, and both enumerate and read the content of any file in it whose extension is a recognized media type.