{
    "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": "2026-08-24T13:11:58.408Z"
    },
    "containers": {
        "cna": {
            "providerMetadata": {
                "orgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10",
                "shortName": "VulnCheck",
                "dateUpdated": "2026-08-24T13:11:58.408Z"
            },
            "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"
                        }
                    ]
                }
            ],
            "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"
                    ]
                },
                {
                    "url": "https://github.com/FreeRDP/FreeRDP/security/advisories/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"
            }
        }
    }
}