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CVE-2026-76840 describes a heap buffer overflow vulnerability in RustDesk's Windows clipboard redirection feature. The flaw resides in CliprdrStream_Read within libs/clipboard/src/windows/wf_cliprdr.c, where a peer-supplied length from a CLIPRDR FileContentsResponse is copied into a fixed-size caller buffer without any upper bound check. A malicious or compromised remote peer can respond to a clipboard file-contents read request with an oversized payload, causing CopyMemory to write attacker-controlled data beyond the heap buffer boundary. The vulnerability is triggered when a local user pastes clipboard file content offered by the remote side, affecting OLE paste consumers such as explorer.exe. The affected code is a fork of FreeRDP's wf_cliprdr.c, where the same defect was tracked as CVE-2026-68579 and fixed in FreeRDP 3.30.0. A fix for RustDesk has been proposed via pull request #15515. Successful exploitation could allow remote code execution or process memory corruption on the client system.

Affected products

  • FreeRDP
  • RustDesk

Related CVE's

  • CVE-2026-68579
  • CVE-2026-76840

Categories

  • Operating Systems
  • Security Tools