RustDesk versions before 1.4.7 contain an uncontrolled speculative memory allocation vulnerability in BytesCodec. Before authentication, the decoder trusts the payload length encoded in a four-byte frame header and reserves that amount before receiving the payload. A crafted header can request up to 1,073,741,823 bytes of capacity, allowing unauthenticated attackers to use concurrent TCP connections to cause memory exhaustion and denial of service. The fix caps header-triggered speculative preallocation at 256 KiB.

RustDesk versions 1.3.9 through 1.4.9 contain a path traversal vulnerability in the macOS clipboard file-paste code path. The application accepts peer-supplied file descriptor names and joins them to the selected target directory without requiring normalized relative paths. A remote peer in an active clipboard file-paste session can use parent-directory components or absolute paths to write files outside the intended target directory at locations writable by the RustDesk process. Commit 6f1eb16 fixes the issue by validating descriptor names and safely joining paths.

RustDesk's Windows clipboard redirection copies a peer-supplied length into a fixed-size caller buffer without an upper bound check. When an OLE paste consumer such as explorer.exe calls IStream::Read with a buffer of cb bytes, CliprdrStream_Read in libs/clipboard/src/windows/wf_cliprdr.c requests that many bytes of a remote file through cliprdr_send_request_filecontents and then executes CopyMemory(pv, clipboard->req_fdata, clipboard->req_fsize), where req_fsize is taken verbatim from the peer's CLIPRDR FileContentsResponse by wf_cliprdr_server_file_contents_response (req_fsize = fileContentsResponse->cbRequested) and is never clamped to cb anywhere in the chain. The function's only length comparison, req_fsize < cb, handles the short-read case and is evaluated after the copy has already occurred. A malicious or compromised peer that answers a small file-contents read with an oversized response therefore writes attacker-chosen data past the end of the paste consumer's heap buffer when the local user pastes clipboard file contents offered by the remote side. The file is a fork of FreeRDP's client/Windows/wf_cliprdr.c, where the same defect is CVE-2026-68579, fixed in FreeRDP 3.30.0.

RustDesk before 1.4.9 does not enforce a session's authorized connection scope on the server side, so a peer granted a limited session type (FileTransfer, PortForward, ViewCamera, or Terminal) can send control messages and login options reserved for a full Remote session. An authenticated remote peer can exploit this missing scope check to act outside its granted scope, injecting out-of-scope control messages to observe and control the host beyond the permissions it was given.

RustDesk gates incoming control messages on per-capability flags rather than on the session's authorized connection type, and a file-transfer session does not clear those flags. A peer holding only a valid FileTransfer authorization can inject keyboard and mouse input and reach the unguarded screenshot and display-capture handlers, acting outside its granted scope.