{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-64034", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-07-19T07:54:57.028Z", "datePublished": "2026-07-19T15:39:23.470Z", "dateUpdated": "2026-08-05T12:38:28.529Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:38:28.529Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: mana: Fix TOCTOU double-fetch of hwc_msg_id from DMA buffer\n\nIn mana_hwc_rx_event_handler(), resp->response.hwc_msg_id is read from\nDMA-coherent memory and bounds-checked, then mana_hwc_handle_resp()\nre-reads the same field from the same DMA buffer for test_bit() and\npointer arithmetic.\n\nDMA-coherent memory is mapped uncacheable on x86 and is shared,\nunencrypted, in Confidential VMs (SEV-SNP/TDX), so each load goes\ndirectly to host-visible memory. A H/W can modify the value\nbetween the check and the use, bypassing the bounds validation.\n\nFix this by reading hwc_msg_id exactly once using READ_ONCE() into a\nstack-local variable in mana_hwc_rx_event_handler(), and passing the\nvalidated value as a parameter to mana_hwc_handle_resp()." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H", "baseScore": 9.3, "baseSeverity": "CRITICAL" }, "scenarios": [ { "lang": "en", "value": "AV:L - Exploitation requires a malicious hypervisor or host that can modify MANA HWC DMA-coherent response buffers between guest kernel loads; it is not reachable by sending network packets to the guest's data path.\nAC:L - The attacker controlling the hypervisor fully controls DMA buffer contents and can reliably flip hwc_msg_id between the validation read and the use in mana_hwc_handle_resp() on uncacheable coherent memory.\nPR:N - The attacking hypervisor needs no guest OS credentials or capabilities; exploitation targets the guest kernel through the virtual device DMA path while the MANA driver is active.\nUI:N - No victim user action is required beyond normal Azure VM operation with the MANA driver loaded and HWC receive buffers posted.\nS:C - The vulnerability crosses the VM/DMA security boundary by allowing a hostile hypervisor to corrupt guest kernel memory that the confidential-guest threat model assumes is protected from host tampering.\nC:H - Out-of-bounds indexing via bypassed hwc_msg_id validation enables reading adjacent kernel heap objects through misdirected caller_ctx access and test_bit() on the inflight bitmap.\nI:H - Host-controlled response data is copied with memcpy() to an out-of-bounds output_buf pointer, enabling arbitrary kernel memory corruption and potential control-flow hijacking.\nA:H - Out-of-bounds caller_ctx access and corrupted completion signaling can cause kernel oops, panic, or hang during HWC response handling." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/net/ethernet/microsoft/mana/hw_channel.c" ], "versions": [ { "version": "ca9c54d2d6a5ab2430c4eda364c77125d62e5e0f", "lessThan": "a201c66edf2ebc6cfdc3813a889ba20fecebfae3", "status": "affected", "versionType": "git" }, { "version": "ca9c54d2d6a5ab2430c4eda364c77125d62e5e0f", "lessThan": "70ad2dff8d052a85dfef15715b531f38a29108cf", "status": "affected", "versionType": "git" }, { "version": "ca9c54d2d6a5ab2430c4eda364c77125d62e5e0f", "lessThan": "566f42fb67a7ebfed6650e407e5b72e6b3e83bf7", "status": "affected", "versionType": "git" }, { "version": "ca9c54d2d6a5ab2430c4eda364c77125d62e5e0f", "lessThan": "6180a06bbc99fd9114b8db4be6c4d46e40f046ef", "status": "affected", "versionType": "git" }, { "version": "ca9c54d2d6a5ab2430c4eda364c77125d62e5e0f", "lessThan": "09ec063d87c2dd3fa6f3561361a017bd882e9f37", "status": "affected", "versionType": "git" }, { "version": "ca9c54d2d6a5ab2430c4eda364c77125d62e5e0f", "lessThan": "3c4db56ccd13dd020fbf43afabaee74a40ec75e4", "status": "affected", "versionType": "git" }, { "version": "ca9c54d2d6a5ab2430c4eda364c77125d62e5e0f", "lessThan": "35f0f0a2536a4d604b4dbad92c85c4a8fdebb870", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/net/ethernet/microsoft/mana/hw_channel.c" ], "versions": [ { "version": "5.13", "status": "affected" }, { "version": "0", "lessThan": "5.13", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.209", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.175", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.142", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.92", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.34", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.0.11", "lessThanOrEqual": "7.0.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.1", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.13", "versionEndExcluding": "5.15.209" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.13", "versionEndExcluding": "6.1.175" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.13", "versionEndExcluding": "6.6.142" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.13", "versionEndExcluding": "6.12.92" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.13", "versionEndExcluding": "6.18.34" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.13", "versionEndExcluding": "7.0.11" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.13", "versionEndExcluding": "7.1" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/a201c66edf2ebc6cfdc3813a889ba20fecebfae3" }, { "url": "https://git.kernel.org/stable/c/70ad2dff8d052a85dfef15715b531f38a29108cf" }, { "url": "https://git.kernel.org/stable/c/566f42fb67a7ebfed6650e407e5b72e6b3e83bf7" }, { "url": "https://git.kernel.org/stable/c/6180a06bbc99fd9114b8db4be6c4d46e40f046ef" }, { "url": "https://git.kernel.org/stable/c/09ec063d87c2dd3fa6f3561361a017bd882e9f37" }, { "url": "https://git.kernel.org/stable/c/3c4db56ccd13dd020fbf43afabaee74a40ec75e4" }, { "url": "https://git.kernel.org/stable/c/35f0f0a2536a4d604b4dbad92c85c4a8fdebb870" } ], "title": "net: mana: Fix TOCTOU double-fetch of hwc_msg_id from DMA buffer", "x_generator": { "engine": "bippy-1.2.0" } } } }