{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-76840","assignerOrgId":"83251b91-4cc7-4094-a5c7-464a1b83ea10","state":"PUBLISHED","assignerShortName":"VulnCheck","dateReserved":"2026-08-19T20:34:19.724Z","datePublished":"2026-08-24T13:11:58.408Z","dateUpdated":"2026-10-01T15:21:11.754Z"},"containers":{"cna":{"providerMetadata":{"orgId":"83251b91-4cc7-4094-a5c7-464a1b83ea10","shortName":"VulnCheck","dateUpdated":"2026-10-01T15:21:11.754Z"},"datePublic":"2026-08-18T00:00:00.000Z","title":"RustDesk through 1.4.9 Heap Buffer Overflow via Unvalidated CLIPRDR FileContentsResponse Length","descriptions":[{"lang":"en","value":"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."}],"problemTypes":[{"descriptions":[{"lang":"en","cweId":"CWE-787","description":"Out-of-bounds Write","type":"CWE"}]},{"descriptions":[{"lang":"en","cweId":"CWE-20","description":"Improper Input Validation","type":"CWE"}]}],"affected":[{"vendor":"rustdesk","product":"rustdesk","collectionURL":"https://github.com/rustdesk/rustdesk","packageName":"rustdesk","defaultStatus":"unaffected","versions":[{"version":"0","lessThanOrEqual":"1.4.9","status":"affected","versionType":"semver"}]}],"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:a:rustdesk:rustdesk:*:*:*:*:*:*:*:*","versionEndIncluding":"1.4.9"}]}]}],"metrics":[{"format":"CVSS","cvssV4_0":{"version":"4.0","vectorString":"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","baseScore":8.5,"baseSeverity":"HIGH","attackVector":"NETWORK","attackComplexity":"LOW","attackRequirements":"NONE","privilegesRequired":"NONE","userInteraction":"PASSIVE","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"NONE","vulnAvailabilityImpact":"HIGH","subConfidentialityImpact":"LOW","subIntegrityImpact":"HIGH","subAvailabilityImpact":"HIGH"}},{"format":"CVSS","cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:H/A:H","baseScore":9.6,"baseSeverity":"CRITICAL","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"REQUIRED","scope":"CHANGED","confidentialityImpact":"LOW","integrityImpact":"HIGH","availabilityImpact":"HIGH"}}],"references":[{"url":"https://github.com/rustdesk/rustdesk","tags":["product"]},{"url":"https://github.com/rustdesk/rustdesk/blob/1.4.9/libs/clipboard/src/windows/wf_cliprdr.c","tags":["technical-description"]},{"url":"https://github.com/rustdesk/rustdesk/pull/15515","tags":["issue-tracking","patch"]},{"url":"https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-m37j-jcr2-8gcc","name":"GitHub Security Advisory (GHSA-m37j-jcr2-8gcc)","tags":["third-party-advisory"]},{"name":"VulnCheck Advisory: RustDesk through 1.4.9 Heap Buffer Overflow via Unvalidated CLIPRDR FileContentsResponse Length","tags":["third-party-advisory"],"url":"https://www.vulncheck.com/advisories/rustdesk-through-heap-buffer-overflow-via-unvalidated-cliprdr-filecontentsresponse-length"}],"credits":[{"lang":"en","value":"Michael Holmquist","type":"finder"}],"x_generator":{"engine":"vulncheck-endgame"}},"adp":[{"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-08-24T16:26:40.462428Z","id":"CVE-2026-76840","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"title":"CISA ADP Vulnrichment","providerMetadata":{"orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP","dateUpdated":"2026-08-24T16:27:03.717Z"}}]}}