{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-89743", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-11T19:38:34.761Z", "datePublished": "2026-09-11T19:46:49.261Z", "dateUpdated": "2026-10-19T08:51:57.186Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-19T08:51:57.186Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmisc: nsm: bound the device-reported response length\n\nnsm_sendrecv_msg_locked() stores the virtqueue used-ring length reported\nby the NSM device into msg->resp.len without bounding it to the response\nbuffer. A malicious or buggy backend can report a length larger than the\nresponse buffer; parse_resp_raw() then copies that many bytes out of the\nfixed buffer to user space, disclosing adjacent kernel heap (an\nout-of-bounds read). The request path already floors its length in\nfill_req_raw(); the response path lacks the symmetric check.\n\nClamp the stored length to the size of the response buffer. Well-behaved\ndevices report no more than the posted buffer size, so conforming traffic\nis unaffected." } ], "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 - A malicious or buggy virtio-nsm backend (hypervisor, QEMU virtio-nsm, or vhost-user device) over-reports the used-ring length consumed by nsm_sendrecv_msg_locked(); the path is local ioctl on /dev/nsm plus virtio, not a network protocol.\nAC:L - The backend deterministically sets the 32-bit used-ring length on each completion, and a local NSM_IOCTL_RAW caller supplies the response iovec that parse_resp_raw() uses as the other copy bound; no race or attacker-uncontrollable layout is required.\nPR:N - The driver registers /dev/nsm as mode 0666 and nsm_dev_ioctl() has no capable() check, so any local process can issue NSM_IOCTL_RAW; a malicious virtio backend also needs no guest credentials.\nUI:N - The attacker opens /dev/nsm and issues NSM_IOCTL_RAW from their own process (the ioctl does not cap response.len to NSM_RESPONSE_MAX_SIZE); no separate victim must mount, click, or otherwise interact.\nS:U - The out-of-bounds read and any resulting oops occur in the guest kernel that hosts the NSM frontend; this is device-to-guest impact, not a guest-to-host, IOMMU, or cross-VM escape.\nC:H - parse_resp_raw() copy_to_user() copies min(user_len, unbounded device len) from the 0x3000-byte resp->data array, so an over-reported length reads adjacent kmalloc heap and returns that kernel memory to userspace.\nI:N - The oversized copy writes only into the ioctl caller's userspace buffer; kernel memory is only read, with no out-of-bounds write, use-after-free, or control-flow hijack primitive.\nA:H - A device-chosen length up to 4GiB drives copy_to_user() past the nsm slab object into unmapped or guarded memory, causing a guest kernel oops or panic that can be repeated on every NSM request." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/misc/nsm.c" ], "versions": [ { "version": "b9873755a6c8ccfce79094c4dce9efa3ecb1a749", "lessThan": "339f19b9a6171289b0e797deb8bda80b9a1fcc30", "status": "affected", "versionType": "git" }, { "version": "b9873755a6c8ccfce79094c4dce9efa3ecb1a749", "lessThan": "29e634a18957acda11383a15ab98a91c4ae9e294", "status": "affected", "versionType": "git" }, { "version": "b9873755a6c8ccfce79094c4dce9efa3ecb1a749", "lessThan": "2aa0fb9c96f894a9c179a48e7522ea6705800adf", "status": "affected", "versionType": "git" }, { "version": "b9873755a6c8ccfce79094c4dce9efa3ecb1a749", "lessThan": "808e530654a5354e6df78863a5d61e4d44e67235", "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/misc/nsm.c" ], "versions": [ { "version": "6.8", "status": "affected" }, { "version": "0", "lessThan": "6.8", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.109", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.50", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2.4", "lessThanOrEqual": "7.2.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.3", "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": "6.8", "versionEndExcluding": "6.12.109" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.8", "versionEndExcluding": "6.18.50" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.8", "versionEndExcluding": "7.2.4" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.8", "versionEndExcluding": "7.3" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/339f19b9a6171289b0e797deb8bda80b9a1fcc30" }, { "url": "https://git.kernel.org/stable/c/29e634a18957acda11383a15ab98a91c4ae9e294" }, { "url": "https://git.kernel.org/stable/c/2aa0fb9c96f894a9c179a48e7522ea6705800adf" }, { "url": "https://git.kernel.org/stable/c/808e530654a5354e6df78863a5d61e4d44e67235" } ], "title": "misc: nsm: bound the device-reported response length", "x_generator": { "engine": "bippy-1.2.0" } } } }