{"id":"CVE-2026-76840","aliases":["EUVD-2026-64846","GHSA-8m44-j2jr-wmrp","GHSA-m37j-jcr2-8gcc"],"status":"published","title":"RustDesk through 1.4.9 Heap Buffer Overflow via Unvalidated CLIPRDR FileContentsResponse Length","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-\u003ereq_fdata, clipboard-\u003ereq_fsize), where req_fsize is taken verbatim from the peer's CLIPRDR FileContentsResponse by wf_cliprdr_server_file_contents_response (req_fsize = fileContentsResponse-\u003ecbRequested) and is never clamped to cb anywhere in the chain. The function's only length comparison, req_fsize \u003c 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.","severity":{"version":"4.0","score":8.5,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:L/SI:H/SA:H","level":"high","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-10","score":0.00433,"percentile":0.3788,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-20","CWE-787"],"published":"2026-08-02T12:15:26.483Z","modified":"2026-11-08T14:08:52Z","products":[{"vendor":"rustdesk","product":"rustdesk"}],"references":[{"url":"https://github.com/rustdesk/rustdesk","tags":["product","package"]},{"url":"https://github.com/rustdesk/rustdesk/blob/1.4.9/libs/clipboard/src/windows/wf_cliprdr.c","tags":["technical-description","article"]},{"url":"https://github.com/rustdesk/rustdesk/pull/15515","tags":["issue-tracking","patch","fix"]},{"url":"https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-m37j-jcr2-8gcc","tags":["third-party-advisory","vendor-advisory","advisory"]},{"url":"https://www.vulncheck.com/advisories/rustdesk-through-heap-buffer-overflow-via-unvalidated-cliprdr-filecontentsresponse-length","tags":["third-party-advisory","advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-76840","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-8m44-j2jr-wmrp"},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/68xxx/CVE-2026-68579.json","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-68579","tags":["advisory"]},{"url":"https://www.vulncheck.com/advisories/freerdp-before-heap-overflow-via-cliprdrstream-read","tags":["advisory"]},{"url":"https://github.com/FreeRDP/FreeRDP/commit/5e8e987b469b60a3bafadf8f5afc40f91c09f458","tags":["fix"]},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/76xxx/CVE-2026-76840.json","tags":["advisory"]}],"sources":{"cve":[{"id":"CVE-2026-76840","title":"RustDesk through 1.4.9 Heap Buffer Overflow via Unvalidated CLIPRDR FileContentsResponse Length","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-\u003ereq_fdata, clipboard-\u003ereq_fsize), where req_fsize is taken verbatim from the peer's CLIPRDR FileContentsResponse by wf_cliprdr_server_file_contents_response (req_fsize = fileContentsResponse-\u003ecbRequested) and is never clamped to cb anywhere in the chain. The function's only length comparison, req_fsize \u003c 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.","status":"published","published":"2026-08-24T13:11:58.408Z","modified":"2026-11-08T14:08:52.577Z","cvss":[{"version":"4.0","score":8.5,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:L/SI:H/SA:H","level":"high","assessor":"cna"},{"version":"3.1","score":9.6,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:H/A:H","level":"critical","assessor":"cna"}],"cwes":["CWE-787","CWE-20"],"updated_at":"2026-11-08T15:43:34.234229Z"}],"euvd":[{"id":"EUVD-2026-64846","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-\u003ereq_fdata, clipboard-\u003ereq_fsize), where req_fsize is taken verbatim from the peer's CLIPRDR FileContentsResponse by wf_cliprdr_server_file_contents_response (req_fsize = fileContentsResponse-\u003ecbRequested) and is never clamped to cb anywhere in the chain. The function's only length comparison, req_fsize \u003c 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.","status":"published","published":"2026-08-24T13:11:58Z","modified":"2026-11-08T14:08:52Z","cvss":[{"version":"4.0","score":8.5,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:L/SI:H/SA:H","level":"high"}],"updated_at":"2026-11-08T15:13:06.469155Z"}],"ghsa":[{"id":"GHSA-8m44-j2jr-wmrp","title":"RustDesk's Windows clipboard redirection copies a peer-supplied length into a fixed-size caller...","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-\u003ereq_fdata, clipboard-\u003ereq_fsize), where req_fsize is taken verbatim from the peer's CLIPRDR FileContentsResponse by wf_cliprdr_server_file_contents_response (req_fsize = fileContentsResponse-\u003ecbRequested) and is never clamped to cb anywhere in the chain. The function's only length comparison, req_fsize \u003c 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.","status":"published","published":"2026-08-24T15:31:51Z","modified":"2026-08-24T15:31:57Z","cvss":[{"version":"4.0","score":8.5,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:L/SI:H/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"high"},{"version":"3.1","score":9.6,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:H/A:H","level":"critical"}],"cwes":["CWE-20"],"updated_at":"2026-11-02T15:10:53.487857Z"}],"nvd":[{"id":"CVE-2026-76840","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-\u003ereq_fdata, clipboard-\u003ereq_fsize), where req_fsize is taken verbatim from the peer's CLIPRDR FileContentsResponse by wf_cliprdr_server_file_contents_response (req_fsize = fileContentsResponse-\u003ecbRequested) and is never clamped to cb anywhere in the chain. The function's only length comparison, req_fsize \u003c 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.","status":"published","published":"2026-08-24T14:17:01.55Z","modified":"2026-10-14T13:10:00.187Z","cvss":[{"version":"4.0","score":8.5,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:L/SI:H/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"high","assessor":"secondary"},{"version":"3.1","score":9.6,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:H/A:H","level":"critical","assessor":"secondary"}],"cwes":["CWE-20","CWE-787"],"updated_at":"2026-11-02T14:12:41.018848Z"}],"osv":[{"id":"CVE-2026-68579","title":"FreeRDP before 3.30.0 Heap Overflow via CliprdrStream_Read","description":"FreeRDP before 3.30.0 (\u003c= 3.29.0) contains a heap-based buffer overflow in the Windows clipboard client's CliprdrStream_Read function (client/Windows/wf_cliprdr.c). When an OLE paste consumer (e.g. explorer.exe) calls IStream::Read with a fixed-size buffer of cb bytes, CliprdrStream_Read requests file contents from the RDP server and then copies the response into the caller's buffer using the server-supplied length (req_fsize) instead of cb. A malicious or compromised RDP server can return an oversized CB_FILECONTENTS_RESPONSE, causing an out-of-bounds write of attacker-controlled data into the paste consumer's heap buffer when a user pastes server-offered clipboard file contents.","status":"published","published":"2026-08-02T12:15:26.483Z","modified":"2026-10-28T02:30:23.900575018Z","cvss":[{"version":"4.0","score":8.7,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N","level":"high"}],"cwes":["CWE-787"],"updated_at":"2026-11-02T15:45:14.808935Z"},{"id":"CVE-2026-76840","title":"RustDesk through 1.4.9 Heap Buffer Overflow via Unvalidated CLIPRDR FileContentsResponse Length","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-\u003ereq_fdata, clipboard-\u003ereq_fsize), where req_fsize is taken verbatim from the peer's CLIPRDR FileContentsResponse by wf_cliprdr_server_file_contents_response (req_fsize = fileContentsResponse-\u003ecbRequested) and is never clamped to cb anywhere in the chain. The function's only length comparison, req_fsize \u003c 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.","status":"published","published":"2026-08-24T13:11:58.408Z","modified":"2026-11-09T02:47:16.659558108Z","cvss":[{"version":"4.0","score":8.5,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:L/SI:H/SA:H","level":"high"}],"cwes":["CWE-20","CWE-787"],"updated_at":"2026-11-09T03:16:17.543303Z"}]}}