CVE-2026-64456

{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-64456", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-07-19T15:36:31.789Z", "datePublished": "2026-07-25T08:51:24.659Z", "dateUpdated": "2026-10-19T20:38:30.595Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-17T04:56:00.610Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nhwrng: virtio: clamp device-reported used.len at copy_data()\n\nrandom_recv_done() stores the device-reported used.len directly into\nvi->data_avail. copy_data() then indexes vi->data[] using\nvi->data_idx (advanced by previous copy_data() calls) and issues a\nmemcpy() without re-validating either value against the posted\nbuffer size sizeof(vi->data) (SMP_CACHE_BYTES bytes, typically 32\nor 64).\n\nA malicious or buggy virtio-rng backend can set used.len beyond\nsizeof(vi->data), steering the memcpy() past the end of the inline\narray into adjacent kmalloc-1k slab bytes. hwrng_fillfn() mixes\nthose bytes into the guest RNG, and guest root can also observe\nthem directly via /dev/hwrng.\n\nConcrete impact is inside the guest:\n\n - Memory-safety / hardening: any virtio-rng backend that\n over-reports used.len causes the driver to read past vi->data\n into unrelated slab contents. hwrng_fillfn() is a kernel thread\n that runs as soon as the device is probed; no guest userspace\n interaction is required to first-trigger the OOB.\n\n - Cross-boundary leak (confidential-compute threat model): a\n malicious hypervisor cooperating with a malicious or compromised\n guest root userspace can use /dev/hwrng as a leak channel for\n guest-kernel heap data. The host sets a large used.len, guest\n root reads /dev/hwrng, and the returned bytes contain guest\n kernel slab contents that were adjacent to vi->data. In\n practice, confidential-compute guests (SEV-SNP, TDX) usually\n disable virtio-rng entirely, so this path is narrow, but the\n fix is still worth carrying because the underlying\n memory-safety bug contaminates the guest RNG on any host.\n\nKASAN confirms the OOB on a 7.1-rc4 guest whose virtio-rng backend\nhas been patched to report used.len = 0x10000:\n\n BUG: KASAN: slab-out-of-bounds in virtio_read+0x394/0x5d0\n Read of size 64 at addr ffff88800ae0ba20 by task hwrng/52\n Call Trace:\n __asan_memcpy+0x23/0x60\n virtio_read+0x394/0x5d0\n hwrng_fillfn+0xb2/0x470\n kthread+0x2cc/0x3a0\n Allocated by task 1:\n probe_common+0xa5/0x660\n virtio_dev_probe+0x549/0xbc0\n The buggy address belongs to the object at ffff88800ae0b800\n which belongs to the cache kmalloc-1k of size 1024\n The buggy address is located 0 bytes to the right of\n allocated 544-byte region [ffff88800ae0b800, ffff88800ae0ba20)\n\nSame class of bug as commit c04db81cd028 (\"net/9p: Fix buffer\noverflow in USB transport layer\"), which hardened\nusb9pfs_rx_complete() against unchecked device-reported length in\nthe USB 9p transport.\n\nWith the clamp at point of use and array_index_nospec() in place,\nthe same harness boots cleanly: copy_data() returns zero for the\nbogus report, the device-supplied bytes after data_idx are\ndiscarded, and the driver issues a fresh request."}], "metrics": [{"cvssV3_1": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H", "baseScore": 7.7, "baseSeverity": "HIGH"}, "scenarios": [{"lang": "en", "value": "AV:L - The attacker must control a virtio-rng backend or hypervisor locally attached to the guest; no network or physical packet path reaches this driver.\nAC:L - The backend directly controls the 32-bit used.len and can deterministically over-report it without winning a race or manipulating an uncertain memory layout.\nPR:N - No privileges inside the vulnerable guest are required because the hwrng kernel thread automatically consumes backend completions after device registration.\nUI:N - The automatically started hwrng thread triggers the out-of-bounds read without any victim action or guest userspace request.\nS:U - The vulnerable driver and the affected memory, RNG state, and availability all belong to the same guest-kernel security authority; this is not a guest-to-host escape.\nC:H - Repeated bounded copies advance through a device-selected, potentially enormous length, producing sequential out-of-bounds reads of guest-kernel heap memory that guest root can observe through /dev/hwrng.\nI:N - The memcpy destination remains bounded by the hwrng core buffer, so the flaw provides no out-of-bounds write, use-after-free, or control-flow modification primitive.\nA:H - A sufficiently large reported length drives reads beyond valid slab memory, causing a kernel out-of-bounds fault, oops, or panic, and the malicious backend can trigger it repeatedly."}]}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["drivers/char/hw_random/virtio-rng.c"], "versions": [{"version": "f7f510ec195781c857ab76366a3e1c59e1caae42", "lessThan": "3aa3e89cf80721c8d382b4c1a2b70a0449dad4a5", "status": "affected", "versionType": "git"}, {"version": "f7f510ec195781c857ab76366a3e1c59e1caae42", "lessThan": "63335e7b638ae70028ae285bb95153874a8bc852", "status": "affected", "versionType": "git"}, {"version": "f7f510ec195781c857ab76366a3e1c59e1caae42", "lessThan": "2e788948ff2a13358a303af112497a63201c5739", "status": "affected", "versionType": "git"}, {"version": "f7f510ec195781c857ab76366a3e1c59e1caae42", "lessThan": "fde19b0d4eeabae042519313c843fe6f27d41e9d", "status": "affected", "versionType": "git"}, {"version": "f7f510ec195781c857ab76366a3e1c59e1caae42", "lessThan": "81dd21b5f0c299cc7b5bf84f04a61938559d20e6", "status": "affected", "versionType": "git"}, {"version": "f7f510ec195781c857ab76366a3e1c59e1caae42", "lessThan": "285e17c44e3873a73460f294acbd64018ff64385", "status": "affected", "versionType": "git"}, {"version": "f7f510ec195781c857ab76366a3e1c59e1caae42", "lessThan": "92d5736a62040ec1cfff23ea57e6599301690ad5", "status": "affected", "versionType": "git"}, {"version": "f7f510ec195781c857ab76366a3e1c59e1caae42", "lessThan": "e3046eeada299f917a8ad883af4434bfb86556b1", "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/char/hw_random/virtio-rng.c"], "versions": [{"version": "2.6.26", "status": "affected"}, {"version": "0", "lessThan": "2.6.26", "status": "unaffected", "versionType": "semver"}, {"version": "5.10.261", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver"}, {"version": "5.15.212", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.1.178", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.6.145", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.12.96", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.18.39", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.1.4", "lessThanOrEqual": "7.1.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.2", "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": "2.6.26", "versionEndExcluding": "5.10.261"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.26", "versionEndExcluding": "5.15.212"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.26", "versionEndExcluding": "6.1.178"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.26", "versionEndExcluding": "6.6.145"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.26", "versionEndExcluding": "6.12.96"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.26", "versionEndExcluding": "6.18.39"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.26", "versionEndExcluding": "7.1.4"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.26", "versionEndExcluding": "7.2"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/3aa3e89cf80721c8d382b4c1a2b70a0449dad4a5"}, {"url": "https://git.kernel.org/stable/c/63335e7b638ae70028ae285bb95153874a8bc852"}, {"url": "https://git.kernel.org/stable/c/2e788948ff2a13358a303af112497a63201c5739"}, {"url": "https://git.kernel.org/stable/c/fde19b0d4eeabae042519313c843fe6f27d41e9d"}, {"url": "https://git.kernel.org/stable/c/81dd21b5f0c299cc7b5bf84f04a61938559d20e6"}, {"url": "https://git.kernel.org/stable/c/285e17c44e3873a73460f294acbd64018ff64385"}, {"url": "https://git.kernel.org/stable/c/92d5736a62040ec1cfff23ea57e6599301690ad5"}, {"url": "https://git.kernel.org/stable/c/e3046eeada299f917a8ad883af4434bfb86556b1"}], "title": "hwrng: virtio: clamp device-reported used.len at copy_data()", "x_generator": {"engine": "bippy-1.2.0"}}, "adp": [{"metrics": [{"other": {"type": "ssvc", "content": {"id": "CVE-2026-64456", "role": "CISA Coordinator", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "partial"}], "version": "2.0.3", "timestamp": "2026-10-16T15:41:09.503091Z"}}}], "problemTypes": [{"descriptions": [{"lang": "en", "type": "CWE", "cweId": "CWE-125", "description": "CWE-125 Out-of-bounds Read"}]}], "title": "CISA ADP Vulnrichment", "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-10-19T20:38:30.595Z"}}]}}

{"dataType": "CVE_RECORD", "containers": {"adp": [{"title": "CISA ADP Vulnrichment", "metrics": [{"other": {"type": "ssvc", "content": {"id": "CVE-2026-64456", "role": "CISA Coordinator", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "partial"}], "version": "2.0.3", "timestamp": "2026-10-16T15:41:09.503091Z"}}}], "problemTypes": [{"descriptions": [{"lang": "en", "type": "CWE", "cweId": "CWE-125", "description": "CWE-125 Out-of-bounds Read"}]}], "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-10-16T15:41:10.136Z"}}], "cna": {"title": "hwrng: virtio: clamp device-reported used.len at copy_data()", "metrics": [{"cvssV3_1": {"version": "3.1", "baseScore": 7.7, "baseSeverity": "HIGH", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H"}, "scenarios": [{"lang": "en", "value": "AV:L - The attacker must control a virtio-rng backend or hypervisor locally attached to the guest; no network or physical packet path reaches this driver.\nAC:L - The backend directly controls the 32-bit used.len and can deterministically over-report it without winning a race or manipulating an uncertain memory layout.\nPR:N - No privileges inside the vulnerable guest are required because the hwrng kernel thread automatically consumes backend completions after device registration.\nUI:N - The automatically started hwrng thread triggers the out-of-bounds read without any victim action or guest userspace request.\nS:U - The vulnerable driver and the affected memory, RNG state, and availability all belong to the same guest-kernel security authority; this is not a guest-to-host escape.\nC:H - Repeated bounded copies advance through a device-selected, potentially enormous length, producing sequential out-of-bounds reads of guest-kernel heap memory that guest root can observe through /dev/hwrng.\nI:N - The memcpy destination remains bounded by the hwrng core buffer, so the flaw provides no out-of-bounds write, use-after-free, or control-flow modification primitive.\nA:H - A sufficiently large reported length drives reads beyond valid slab memory, causing a kernel out-of-bounds fault, oops, or panic, and the malicious backend can trigger it repeatedly."}]}], "affected": [{"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "product": "Linux", "versions": [{"status": "affected", "version": "f7f510ec195781c857ab76366a3e1c59e1caae42", "lessThan": "3aa3e89cf80721c8d382b4c1a2b70a0449dad4a5", "versionType": "git"}, {"status": "affected", "version": "f7f510ec195781c857ab76366a3e1c59e1caae42", "lessThan": "63335e7b638ae70028ae285bb95153874a8bc852", "versionType": "git"}, {"status": "affected", "version": "f7f510ec195781c857ab76366a3e1c59e1caae42", "lessThan": "2e788948ff2a13358a303af112497a63201c5739", "versionType": "git"}, {"status": "affected", "version": "f7f510ec195781c857ab76366a3e1c59e1caae42", "lessThan": "fde19b0d4eeabae042519313c843fe6f27d41e9d", "versionType": "git"}, {"status": "affected", "version": "f7f510ec195781c857ab76366a3e1c59e1caae42", "lessThan": "81dd21b5f0c299cc7b5bf84f04a61938559d20e6", "versionType": "git"}, {"status": "affected", "version": "f7f510ec195781c857ab76366a3e1c59e1caae42", "lessThan": "285e17c44e3873a73460f294acbd64018ff64385", "versionType": "git"}, {"status": "affected", "version": "f7f510ec195781c857ab76366a3e1c59e1caae42", "lessThan": "92d5736a62040ec1cfff23ea57e6599301690ad5", "versionType": "git"}, {"status": "affected", "version": "f7f510ec195781c857ab76366a3e1c59e1caae42", "lessThan": "e3046eeada299f917a8ad883af4434bfb86556b1", "versionType": "git"}], "programFiles": ["drivers/char/hw_random/virtio-rng.c"], "defaultStatus": "unaffected"}, {"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "product": "Linux", "versions": [{"status": "affected", "version": "2.6.26"}, {"status": "unaffected", "version": "0", "lessThan": "2.6.26", "versionType": "semver"}, {"status": "unaffected", "version": "5.10.261", "versionType": "semver", "lessThanOrEqual": "5.10.*"}, {"status": "unaffected", "version": "5.15.212", "versionType": "semver", "lessThanOrEqual": "5.15.*"}, {"status": "unaffected", "version": "6.1.178", "versionType": "semver", "lessThanOrEqual": "6.1.*"}, {"status": "unaffected", "version": "6.6.145", "versionType": "semver", "lessThanOrEqual": "6.6.*"}, {"status": "unaffected", "version": "6.12.96", "versionType": "semver", "lessThanOrEqual": "6.12.*"}, {"status": "unaffected", "version": "6.18.39", "versionType": "semver", "lessThanOrEqual": "6.18.*"}, {"status": "unaffected", "version": "7.1.4", "versionType": "semver", "lessThanOrEqual": "7.1.*"}, {"status": "unaffected", "version": "7.2", "versionType": "original_commit_for_fix", "lessThanOrEqual": "*"}], "programFiles": ["drivers/char/hw_random/virtio-rng.c"], "defaultStatus": "affected"}], "references": [{"url": "https://git.kernel.org/stable/c/3aa3e89cf80721c8d382b4c1a2b70a0449dad4a5"}, {"url": "https://git.kernel.org/stable/c/63335e7b638ae70028ae285bb95153874a8bc852"}, {"url": "https://git.kernel.org/stable/c/2e788948ff2a13358a303af112497a63201c5739"}, {"url": "https://git.kernel.org/stable/c/fde19b0d4eeabae042519313c843fe6f27d41e9d"}, {"url": "https://git.kernel.org/stable/c/81dd21b5f0c299cc7b5bf84f04a61938559d20e6"}, {"url": "https://git.kernel.org/stable/c/285e17c44e3873a73460f294acbd64018ff64385"}, {"url": "https://git.kernel.org/stable/c/92d5736a62040ec1cfff23ea57e6599301690ad5"}, {"url": "https://git.kernel.org/stable/c/e3046eeada299f917a8ad883af4434bfb86556b1"}], "x_generator": {"engine": "bippy-1.2.0"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nhwrng: virtio: clamp device-reported used.len at copy_data()\n\nrandom_recv_done() stores the device-reported used.len directly into\nvi->data_avail. copy_data() then indexes vi->data[] using\nvi->data_idx (advanced by previous copy_data() calls) and issues a\nmemcpy() without re-validating either value against the posted\nbuffer size sizeof(vi->data) (SMP_CACHE_BYTES bytes, typically 32\nor 64).\n\nA malicious or buggy virtio-rng backend can set used.len beyond\nsizeof(vi->data), steering the memcpy() past the end of the inline\narray into adjacent kmalloc-1k slab bytes. hwrng_fillfn() mixes\nthose bytes into the guest RNG, and guest root can also observe\nthem directly via /dev/hwrng.\n\nConcrete impact is inside the guest:\n\n - Memory-safety / hardening: any virtio-rng backend that\n over-reports used.len causes the driver to read past vi->data\n into unrelated slab contents. hwrng_fillfn() is a kernel thread\n that runs as soon as the device is probed; no guest userspace\n interaction is required to first-trigger the OOB.\n\n - Cross-boundary leak (confidential-compute threat model): a\n malicious hypervisor cooperating with a malicious or compromised\n guest root userspace can use /dev/hwrng as a leak channel for\n guest-kernel heap data. The host sets a large used.len, guest\n root reads /dev/hwrng, and the returned bytes contain guest\n kernel slab contents that were adjacent to vi->data. In\n practice, confidential-compute guests (SEV-SNP, TDX) usually\n disable virtio-rng entirely, so this path is narrow, but the\n fix is still worth carrying because the underlying\n memory-safety bug contaminates the guest RNG on any host.\n\nKASAN confirms the OOB on a 7.1-rc4 guest whose virtio-rng backend\nhas been patched to report used.len = 0x10000:\n\n BUG: KASAN: slab-out-of-bounds in virtio_read+0x394/0x5d0\n Read of size 64 at addr ffff88800ae0ba20 by task hwrng/52\n Call Trace:\n __asan_memcpy+0x23/0x60\n virtio_read+0x394/0x5d0\n hwrng_fillfn+0xb2/0x470\n kthread+0x2cc/0x3a0\n Allocated by task 1:\n probe_common+0xa5/0x660\n virtio_dev_probe+0x549/0xbc0\n The buggy address belongs to the object at ffff88800ae0b800\n which belongs to the cache kmalloc-1k of size 1024\n The buggy address is located 0 bytes to the right of\n allocated 544-byte region [ffff88800ae0b800, ffff88800ae0ba20)\n\nSame class of bug as commit c04db81cd028 (\"net/9p: Fix buffer\noverflow in USB transport layer\"), which hardened\nusb9pfs_rx_complete() against unchecked device-reported length in\nthe USB 9p transport.\n\nWith the clamp at point of use and array_index_nospec() in place,\nthe same harness boots cleanly: copy_data() returns zero for the\nbogus report, the device-supplied bytes after data_idx are\ndiscarded, and the driver issues a fresh request."}], "cpeApplicability": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "5.10.261", "versionStartIncluding": "2.6.26"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "5.15.212", "versionStartIncluding": "2.6.26"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "6.1.178", "versionStartIncluding": "2.6.26"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "6.6.145", "versionStartIncluding": "2.6.26"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "6.12.96", "versionStartIncluding": "2.6.26"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "6.18.39", "versionStartIncluding": "2.6.26"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "7.1.4", "versionStartIncluding": "2.6.26"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "7.2", "versionStartIncluding": "2.6.26"}], "operator": "OR"}]}], "providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-17T04:56:00.610Z"}}}, "cveMetadata": {"cveId": "CVE-2026-64456", "state": "PUBLISHED", "dateUpdated": "2026-10-19T20:38:30.595Z", "dateReserved": "2026-07-19T15:36:31.789Z", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "datePublished": "2026-07-25T08:51:24.659Z", "assignerShortName": "Linux"}, "dataVersion": "5.2"}

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"D913E879-38EC-46AE-9F20-5D3E5F2CDCC2", "vulnerable": true}, {"criteria": "cpe:2.3:o:linux:linux_kernel:2.6.26:rc9:*:*:*:*:*:*", "matchCriteriaId": "B264E869-1A6C-4D85-9944-2E4EB523CD82", "vulnerable": true}], "negate": false, "operator": "OR"}]}], "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nhwrng: virtio: clamp device-reported used.len at copy_data()\n\nrandom_recv_done() stores the device-reported used.len directly into\nvi->data_avail. copy_data() then indexes vi->data[] using\nvi->data_idx (advanced by previous copy_data() calls) and issues a\nmemcpy() without re-validating either value against the posted\nbuffer size sizeof(vi->data) (SMP_CACHE_BYTES bytes, typically 32\nor 64).\n\nA malicious or buggy virtio-rng backend can set used.len beyond\nsizeof(vi->data), steering the memcpy() past the end of the inline\narray into adjacent kmalloc-1k slab bytes. hwrng_fillfn() mixes\nthose bytes into the guest RNG, and guest root can also observe\nthem directly via /dev/hwrng.\n\nConcrete impact is inside the guest:\n\n - Memory-safety / hardening: any virtio-rng backend that\n over-reports used.len causes the driver to read past vi->data\n into unrelated slab contents. hwrng_fillfn() is a kernel thread\n that runs as soon as the device is probed; no guest userspace\n interaction is required to first-trigger the OOB.\n\n - Cross-boundary leak (confidential-compute threat model): a\n malicious hypervisor cooperating with a malicious or compromised\n guest root userspace can use /dev/hwrng as a leak channel for\n guest-kernel heap data. The host sets a large used.len, guest\n root reads /dev/hwrng, and the returned bytes contain guest\n kernel slab contents that were adjacent to vi->data. In\n practice, confidential-compute guests (SEV-SNP, TDX) usually\n disable virtio-rng entirely, so this path is narrow, but the\n fix is still worth carrying because the underlying\n memory-safety bug contaminates the guest RNG on any host.\n\nKASAN confirms the OOB on a 7.1-rc4 guest whose virtio-rng backend\nhas been patched to report used.len = 0x10000:\n\n BUG: KASAN: slab-out-of-bounds in virtio_read+0x394/0x5d0\n Read of size 64 at addr ffff88800ae0ba20 by task hwrng/52\n Call Trace:\n __asan_memcpy+0x23/0x60\n virtio_read+0x394/0x5d0\n hwrng_fillfn+0xb2/0x470\n kthread+0x2cc/0x3a0\n Allocated by task 1:\n probe_common+0xa5/0x660\n virtio_dev_probe+0x549/0xbc0\n The buggy address belongs to the object at ffff88800ae0b800\n which belongs to the cache kmalloc-1k of size 1024\n The buggy address is located 0 bytes to the right of\n allocated 544-byte region [ffff88800ae0b800, ffff88800ae0ba20)\n\nSame class of bug as commit c04db81cd028 (\"net/9p: Fix buffer\noverflow in USB transport layer\"), which hardened\nusb9pfs_rx_complete() against unchecked device-reported length in\nthe USB 9p transport.\n\nWith the clamp at point of use and array_index_nospec() in place,\nthe same harness boots cleanly: copy_data() returns zero for the\nbogus report, the device-supplied bytes after data_idx are\ndiscarded, and the driver issues a fresh request."}], "id": "CVE-2026-64456", "lastModified": "2026-11-12T20:19:36.930", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "baseScore": 7.7, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "NONE", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H", "version": "3.1"}, "exploitabilityScore": 2.5, "impactScore": 5.2, "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-64456", "options": [{"exploitation": "none"}, {"automatable": "no"}, {"technicalImpact": "partial"}], "role": "CISA Coordinator", "timestamp": "2026-10-16T15:41:09.503091Z", "version": "2.0.3"}}]}, "published": "2026-07-25T10:17:30.677", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/285e17c44e3873a73460f294acbd64018ff64385"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/2e788948ff2a13358a303af112497a63201c5739"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/3aa3e89cf80721c8d382b4c1a2b70a0449dad4a5"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/63335e7b638ae70028ae285bb95153874a8bc852"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/81dd21b5f0c299cc7b5bf84f04a61938559d20e6"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/92d5736a62040ec1cfff23ea57e6599301690ad5"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/e3046eeada299f917a8ad883af4434bfb86556b1"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/fde19b0d4eeabae042519313c843fe6f27d41e9d"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Analyzed", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-125"}], "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary"}]}

{"bugzilla": {"description": "kernel: hwrng: virtio: clamp device-reported used.len at copy_data()", "id": "2507255", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2507255"}, "csaw": false, "cvss3": {"cvss3_base_score": "5.5", "cvss3_scoring_vector": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "status": "draft"}, "cwe": "CWE-125", "details": ["A flaw was found in the Linux kernel's virtio-rng driver. A malicious or buggy virtualized hardware random number generator (virtio-rng) backend can report an overly large data length to the guest operating system. This unchecked length can lead to an out-of-bounds read, causing the driver to access memory beyond its intended buffer. This vulnerability can result in information disclosure, where sensitive guest-kernel heap data may be leaked to a malicious hypervisor or a compromised guest root user."], "name": "CVE-2026-64456", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Fix deferred", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Out of support scope", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Fix deferred", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Fix deferred", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Fix deferred", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Fix deferred", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Fix deferred", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Fix deferred", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/a:redhat:hummingbird:1", "fix_state": "Not affected", "impact": "moderate", "package_name": "erlang27", "product_name": "Red Hat Hardened Images"}], "public_date": "2026-07-25T00:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-64456\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-64456\nhttps://lore.kernel.org/linux-cve-announce/2026072542-CVE-2026-64456-ccb5@gregkh/T"], "threat_severity": "Moderate"}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[f7f510ec195781c857ab76366a3e1c59e1caae42,3aa3e89cf80721c8d382b4c1a2b70a0449dad4a5]"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[f7f510ec195781c857ab76366a3e1c59e1caae42,63335e7b638ae70028ae285bb95153874a8bc852]"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[f7f510ec195781c857ab76366a3e1c59e1caae42,2e788948ff2a13358a303af112497a63201c5739]"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[f7f510ec195781c857ab76366a3e1c59e1caae42,fde19b0d4eeabae042519313c843fe6f27d41e9d]"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[f7f510ec195781c857ab76366a3e1c59e1caae42,81dd21b5f0c299cc7b5bf84f04a61938559d20e6]"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[f7f510ec195781c857ab76366a3e1c59e1caae42,285e17c44e3873a73460f294acbd64018ff64385]"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[f7f510ec195781c857ab76366a3e1c59e1caae42,92d5736a62040ec1cfff23ea57e6599301690ad5]"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[f7f510ec195781c857ab76366a3e1c59e1caae42,e3046eeada299f917a8ad883af4434bfb86556b1]"}}], "enrichment": {"confidence": 99.0, "confidence_source": "inferred", "scores": [{"score": 99.0, "source": "inferred"}, {"score": 100.0, "source": "matching"}]}, "original": {"product": "Linux", "source": "cna", "vendor": "Linux"}, "product": "linux_kernel", "vendor": "linux"}, {"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "2.6.26"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[0,2.6.26)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[5.10.261,5.11.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[5.15.212,5.16.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[6.1.178,6.2.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[6.6.145,6.7.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[6.12.96,6.13.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[6.18.39,6.19.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[7.1.4,7.2.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[7.2-rc1,*]"}}], "enrichment": {"confidence": 99.0, "confidence_source": "inferred", "scores": [{"score": 99.0, "source": "inferred"}, {"score": 100.0, "source": "matching"}]}, "original": {"product": "Linux", "source": "cna", "vendor": "Linux"}, "product": "linux_kernel", "vendor": "linux"}], "created": "2026-07-25T19:15:03.262528+00:00", "updated": "2026-08-02T12:45:06.522786+00:00", "vendors": ["linux", "linux$PRODUCT$linux_kernel"]}