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CVE-2026-76840— RustDesk through 1.4.9 Heap Buffer Overflow via Unvalidated CLIPRDR FileContentsResponse Length

Quick assessment

Affected
rustdesk rustdesk
Exploitation
Public or AI PoC available; prioritize validation
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

RustDesk是RustDesk团队开源的一款远程桌面连接软件。 RustDesk 1.4.9及之前版本存在安全漏洞，该漏洞源于Windows剪贴板重定向将对等方提供的长度复制到固定大小缓冲区时缺少上限检查，导致堆缓冲区溢出，可能允许恶意对等方在用户粘贴远程剪贴板文件内容时写入越界数据。

CVSS 9.6 · Critical EPSS 0.43% · P37

Possible ATT&CK Techniques 1 AI

T1059 · Command and Scripting Interpreter

Affected Version Matrix 1

VendorProduct Version RangeStatus
rustdesk rustdesk ≤ 1.4.9 affected
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I. Basic Information for CVE-2026-76840

Vulnerability Information
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Vulnerability Title
RustDesk through 1.4.9 Heap Buffer Overflow via Unvalidated CLIPRDR FileContentsResponse Length
Source: CVE Program / CVE List V5
Vulnerability 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 < 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
跨界内存写
Source: CVE Program / CVE List V5
Vulnerability Title
RustDesk 输入验证错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
RustDesk是RustDesk团队开源的一款远程桌面连接软件。 RustDesk 1.4.9及之前版本存在安全漏洞，该漏洞源于Windows剪贴板重定向将对等方提供的长度复制到固定大小缓冲区时缺少上限检查，导致堆缓冲区溢出，可能允许恶意对等方在用户粘贴远程剪贴板文件内容时写入越界数据。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
rustdesk rustdesk 0 ~ 1.4.9 -

II. Public POCs for CVE-2026-76840

# POC Description Source Link Shenlong Link
AI-Generated POC Premium
Qwen3.6-35B-A3B · 10760 chars
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III. Intelligence Information for CVE-2026-76840

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Patches & Fixes for CVE-2026-76840 (1)

Vendor Advisories for CVE-2026-76840 (1)

News Coverage for CVE-2026-76840 (1)

Vendor Pages for CVE-2026-76840 (1)

IV. Related Vulnerabilities

Same product: rustdesk
Same vendor: rustdesk
Same weakness: CWE-787

V. Comments for CVE-2026-76840

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