A flaw was found in cockpit. The cockpit-storaged module's get_tang_adv() function (pkg/storaged/crypto/tang.jsx) builds curl's argument vector by string concatenation: cockpit.spawn(["curl", "-sSf", url + "/adv"]), with no "--" separator between options and the positional argument. On the Edit-Tang-keyserver path, this url value is read verbatim from a clevis token embedded in the LUKS header of a block device, which is data controlled by whoever can write to or attach that device, not necessarily the Cockpit operator. validate_url() only rejects empty strings and values that fail JavaScript URL parsing; a value such as "-K/var/tmp/stash" parses successfully (hostname "-k") and is accepted. When such a value reaches curl, curl interprets it as the "-K" (config file) option instead of a hostname, loading an attacker-planted curl configuration file. The planted configuration can set "output" to any path the Cockpit session user can write, "url" to a file:// URL to read any file that user can read, or "upload-file" with a remote destination to exfiltrate data -- all running as the Cockpit session user (not root; the LUKS-header read itself runs with superuser privileges via python.spawn(..., {superuser: "require"}), but the subsequent curl invocation does not). A local unprivileged user with a local, active console or desktop login session (not a remote SSH or Cockpit web session) can plant the malicious LUKS header using the standard, default-granted udisks2 org.freedesktop.udisks2.loop-setup polkit permission (allow_active=yes), requiring no elevated privilege. An administrator with Cockpit access who then opens the "Edit Tang keyserver" dialog for that device and clicks Save, without recognizing the prefilled value as a curl option rather than an address, triggers the chain. No non-default configuration is required.