CVE-2026-100388

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.

RustDesk before 1.5.0 on Windows fails to enforce the one-way file transfer option against peer clipboard file requests, allowing authenticated peers to read files from the host clipboard. Attackers can send FormatDataRequest and FileContentsRequest messages to retrieve copied files by guessing the FileGroupDescriptorW format identifier.

RustDesk before version 1.4.7 has an uncontrolled speculative memory allocation vulnerability in BytesCodec. Before authentication, the decoder trusts the payload length in the frame header and reserves memory before receiving data, allowing memory exhaustion via multiple TCP connections.

RustDesk versions 1.3.9 through 1.4.9 contain a path traversal vulnerability in the macOS clipboard file-paste code path. A remote peer can write files outside the intended target directory using parent-directory components or absolute paths.

RustDesk before version 1.4.9 does not enforce the authorized connection scope of a session on the server side. An authenticated remote peer with a limited session type (FileTransfer, PortForward, ViewCamera, or Terminal) can send control messages and login options reserved for a full Remote session.

A vulnerability in RustDesk allows a peer with only FileTransfer authorization to inject keyboard and mouse input and access unguarded screenshot and display-capture handlers. This occurs because incoming control messages are gated on per-capability flags, and a file-transfer session does not clear those flags.