{"id":"CVE-2026-76840","summary":"RustDesk through 1.4.9 Heap Buffer Overflow via Unvalidated CLIPRDR FileContentsResponse Length","details":"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.","aliases":["CVE-2026-68579","GHSA-m37j-jcr2-8gcc"],"modified":"2026-08-30T03:47:27.991839412Z","published":"2026-08-24T13:11:58.408Z","database_specific":{"cna_assigner":"VulnCheck","cwe_ids":["CWE-20","CWE-787"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/76xxx/CVE-2026-76840.json"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/76xxx/CVE-2026-76840.json"},{"type":"ADVISORY","url":"https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-m37j-jcr2-8gcc"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-76840"},{"type":"ADVISORY","url":"https://www.vulncheck.com/advisories/rustdesk-through-heap-buffer-overflow-via-unvalidated-cliprdr-filecontentsresponse-length"},{"type":"FIX","url":"https://github.com/rustdesk/rustdesk/pull/15515"},{"type":"PACKAGE","url":"https://github.com/rustdesk/rustdesk"},{"type":"ARTICLE","url":"https://github.com/rustdesk/rustdesk/blob/1.4.9/libs/clipboard/src/windows/wf_cliprdr.c"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/rustdesk/rustdesk","events":[{"introduced":"0"},{"last_affected":"6c578292e8ebbbec708b76986ba8c4bc7c509747"}],"database_specific":{"extracted_events":[{"introduced":"0"},{"last_affected":"1.4.9"}],"source":"AFFECTED_FIELD"}}],"versions":["1.4.9","1.4.8","1.4.7","1.4.6","nightly","1.4.5","1.4.4","1.4.3","1.4.2","1.4.1","1.4.0","1.3.9","1.3.8","1.3.7","1.3.6","1.3.5","1.3.4","1.3.3","1.3.2","1.3.1","1.3.0","1.2.7","1.2.6","1.2.5","fdroid-version","1.2.4","1.2.3-2","1.2.3-1","1.2.3","1.2.2","1.2.1","1.2.0","1.1.9","1.1.8","1.1.3"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-76840.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V4","score":"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"}]}