CVE-2026-76840
Severity CVSS v4.0:
HIGH
Type:
CWE-20
Input Validation
Publication date:
24/08/2026
Last modified:
24/08/2026
Description
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
Impact
Base Score 4.0
8.50
Severity 4.0
HIGH
Base Score 3.x
9.60
Severity 3.x
CRITICAL
References to Advisories, Solutions, and Tools
- https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-m37j-jcr2-8gcc
- https://github.com/rustdesk/rustdesk
- https://github.com/rustdesk/rustdesk/blob/1.4.9/libs/clipboard/src/windows/wf_cliprdr.c
- https://github.com/rustdesk/rustdesk/pull/15515
- https://www.vulncheck.com/advisories/rustdesk-through-heap-buffer-overflow-via-unvalidated-cliprdr-filecontentsresponse-length