{"api_version":"1","generated_at":"2026-09-14T03:10:53+00:00","cve":"CVE-2026-89743","urls":{"html":"https://cve.report/CVE-2026-89743","api":"https://cve.report/api/cve/CVE-2026-89743.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-89743","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-89743"},"summary":{"title":"misc: nsm: bound the device-reported response length","description":"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.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-09-11 20:20:04","updated_at":"2026-09-13 07:17:38"},"problem_types":[],"metrics":[{"version":"3.1","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","score":"7.7","severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H","data":{"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","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"NONE","availabilityImpact":"HIGH"}},{"version":"3.1","source":"CNA","type":"DECLARED","score":"7.7","severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H","data":{"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","version":"3.1"}}],"references":[{"url":"https://git.kernel.org/stable/c/29e634a18957acda11383a15ab98a91c4ae9e294","name":"https://git.kernel.org/stable/c/29e634a18957acda11383a15ab98a91c4ae9e294","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/808e530654a5354e6df78863a5d61e4d44e67235","name":"https://git.kernel.org/stable/c/808e530654a5354e6df78863a5d61e4d44e67235","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/339f19b9a6171289b0e797deb8bda80b9a1fcc30","name":"https://git.kernel.org/stable/c/339f19b9a6171289b0e797deb8bda80b9a1fcc30","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/2aa0fb9c96f894a9c179a48e7522ea6705800adf","name":"https://git.kernel.org/stable/c/2aa0fb9c96f894a9c179a48e7522ea6705800adf","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-89743","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89743","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected b9873755a6c8ccfce79094c4dce9efa3ecb1a749 339f19b9a6171289b0e797deb8bda80b9a1fcc30 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected b9873755a6c8ccfce79094c4dce9efa3ecb1a749 29e634a18957acda11383a15ab98a91c4ae9e294 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected b9873755a6c8ccfce79094c4dce9efa3ecb1a749 2aa0fb9c96f894a9c179a48e7522ea6705800adf git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected b9873755a6c8ccfce79094c4dce9efa3ecb1a749 808e530654a5354e6df78863a5d61e4d44e67235 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.8","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.8 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.12.109 6.12.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.50 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2.4 7.2.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.3-rc1 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":{"cve_year":"2026","cve_id":"89743","cve":"CVE-2026-89743","epss":"0.001440000","percentile":"0.039760000","score_date":"2026-09-13","updated_at":"2026-09-14 00:18:00"},"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["drivers/misc/nsm.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"339f19b9a6171289b0e797deb8bda80b9a1fcc30","status":"affected","version":"b9873755a6c8ccfce79094c4dce9efa3ecb1a749","versionType":"git"},{"lessThan":"29e634a18957acda11383a15ab98a91c4ae9e294","status":"affected","version":"b9873755a6c8ccfce79094c4dce9efa3ecb1a749","versionType":"git"},{"lessThan":"2aa0fb9c96f894a9c179a48e7522ea6705800adf","status":"affected","version":"b9873755a6c8ccfce79094c4dce9efa3ecb1a749","versionType":"git"},{"lessThan":"808e530654a5354e6df78863a5d61e4d44e67235","status":"affected","version":"b9873755a6c8ccfce79094c4dce9efa3ecb1a749","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["drivers/misc/nsm.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"6.8"},{"lessThan":"6.8","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"6.12.*","status":"unaffected","version":"6.12.109","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.50","versionType":"semver"},{"lessThanOrEqual":"7.2.*","status":"unaffected","version":"7.2.4","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.3-rc1","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.12.109","versionStartIncluding":"6.8","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.50","versionStartIncluding":"6.8","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2.4","versionStartIncluding":"6.8","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.3-rc1","versionStartIncluding":"6.8","vulnerable":true}],"negate":false,"operator":"OR"}]}],"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":{"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","version":"3.1"},"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."}]}],"providerMetadata":{"dateUpdated":"2026-09-13T06:33:52.757Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"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"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-89743","datePublished":"2026-09-11T19:46:49.261Z","dateReserved":"2026-09-11T19:38:34.761Z","dateUpdated":"2026-09-13T06:33:52.757Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-09-11 20:20:04","lastModifiedDate":"2026-09-13 07:17:38","problem_types":[],"metrics":{"cvssMetricV31":[{"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","cvssData":{"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","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"NONE","availabilityImpact":"HIGH"},"exploitabilityScore":2.5,"impactScore":5.2}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"89743","Ordinal":"1","Title":"misc: nsm: bound the device-reported response length","CVE":"CVE-2026-89743","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"89743","Ordinal":"1","NoteData":"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.","Type":"Description","Title":"misc: nsm: bound the device-reported response length"}]}}}