{"api_version":"1","generated_at":"2026-10-27T04:26:19+00:00","cve":"CVE-2026-99017","urls":{"html":"https://cve.report/CVE-2026-99017","api":"https://cve.report/api/cve/CVE-2026-99017.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-99017","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-99017"},"summary":{"title":"riscv: errata: select RISCV_ALTERNATIVE_EARLY for THEAD GHOSTWRITE","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nriscv: errata: select RISCV_ALTERNATIVE_EARLY for THEAD GHOSTWRITE\n\nerrata_probe_ghostwrite() only marks the CPU as vulnerable when it is\ncalled at the RISCV_ALTERNATIVES_EARLY_BOOT stage, and the mitigation\nin ghostwrite_enable_mitigation() only takes effect if the vulnerable\nstate was recorded before the boot alternatives are patched.\n\nThe early boot stage is only executed when CONFIG_RISCV_ALTERNATIVE_EARLY\nis enabled, which currently is only selected by ERRATA_THEAD_MAE. In a\nkernel built with ERRATA_THEAD_GHOSTWRITE=y but ERRATA_THEAD_MAE=n, the\nearly alternatives never run, so ghostwrite_state is never set to\nVULNERABLE: ghostwrite_enable_mitigation() returns false, xtheadvector\nremains enabled, and sysfs reports \"Not affected\" on a vulnerable\nT-Head C9xx CPU.\n\nSelect RISCV_ALTERNATIVE_EARLY from ERRATA_THEAD_GHOSTWRITE so that the\nvulnerability is detected in the early boot stage and the default\nmitigation is applied.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-10-23 13:17:24","updated_at":"2026-10-24 14:16:52"},"problem_types":[],"metrics":[{"version":"3.1","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","score":"7","severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H","data":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7,"baseSeverity":"HIGH","attackVector":"LOCAL","attackComplexity":"HIGH","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"}},{"version":"3.1","source":"CNA","type":"DECLARED","score":"7","severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H","data":{"baseScore":7,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H","version":"3.1"}}],"references":[{"url":"https://git.kernel.org/stable/c/fa465a7819ecbe5801b78c088d3cadaf2664b8ca","name":"https://git.kernel.org/stable/c/fa465a7819ecbe5801b78c088d3cadaf2664b8ca","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/7fee577a2fa78b9a76da015beec1ccf978746ebb","name":"https://git.kernel.org/stable/c/7fee577a2fa78b9a76da015beec1ccf978746ebb","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/298510bbc7c3017c0faf481c6ea66f1065b657b4","name":"https://git.kernel.org/stable/c/298510bbc7c3017c0faf481c6ea66f1065b657b4","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-99017","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-99017","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 4bf97069239bcfca9840936313c7ac35a6e04488 fa465a7819ecbe5801b78c088d3cadaf2664b8ca git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 4bf97069239bcfca9840936313c7ac35a6e04488 7fee577a2fa78b9a76da015beec1ccf978746ebb git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 4bf97069239bcfca9840936313c7ac35a6e04488 298510bbc7c3017c0faf481c6ea66f1065b657b4 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.14","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.14 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.57 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2.11 7.2.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.3 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":null,"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["arch/riscv/Kconfig.errata"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"fa465a7819ecbe5801b78c088d3cadaf2664b8ca","status":"affected","version":"4bf97069239bcfca9840936313c7ac35a6e04488","versionType":"git"},{"lessThan":"7fee577a2fa78b9a76da015beec1ccf978746ebb","status":"affected","version":"4bf97069239bcfca9840936313c7ac35a6e04488","versionType":"git"},{"lessThan":"298510bbc7c3017c0faf481c6ea66f1065b657b4","status":"affected","version":"4bf97069239bcfca9840936313c7ac35a6e04488","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["arch/riscv/Kconfig.errata"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"6.14"},{"lessThan":"6.14","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.57","versionType":"semver"},{"lessThanOrEqual":"7.2.*","status":"unaffected","version":"7.2.11","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.3","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.57","versionStartIncluding":"6.14","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2.11","versionStartIncluding":"6.14","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.3","versionStartIncluding":"6.14","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nriscv: errata: select RISCV_ALTERNATIVE_EARLY for THEAD GHOSTWRITE\n\nerrata_probe_ghostwrite() only marks the CPU as vulnerable when it is\ncalled at the RISCV_ALTERNATIVES_EARLY_BOOT stage, and the mitigation\nin ghostwrite_enable_mitigation() only takes effect if the vulnerable\nstate was recorded before the boot alternatives are patched.\n\nThe early boot stage is only executed when CONFIG_RISCV_ALTERNATIVE_EARLY\nis enabled, which currently is only selected by ERRATA_THEAD_MAE. In a\nkernel built with ERRATA_THEAD_GHOSTWRITE=y but ERRATA_THEAD_MAE=n, the\nearly alternatives never run, so ghostwrite_state is never set to\nVULNERABLE: ghostwrite_enable_mitigation() returns false, xtheadvector\nremains enabled, and sysfs reports \"Not affected\" on a vulnerable\nT-Head C9xx CPU.\n\nSelect RISCV_ALTERNATIVE_EARLY from ERRATA_THEAD_GHOSTWRITE so that the\nvulnerability is detected in the early boot stage and the default\nmitigation is applied."}],"metrics":[{"cvssV3_1":{"baseScore":7,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H","version":"3.1"},"scenarios":[{"lang":"en","value":"AV:L - A local process executes the GhostWrite vector sequence; its first vector instruction follows handle_exception() through do_trap_insn_illegal() to riscv_v_first_use_handler(), after which the faulty store executes in U-mode. No network protocol carries the causal input.\nAC:H - Exposure requires a vulnerable T-Head C9xx with xtheadvector and the unusual build combination ERRATA_THEAD_GHOSTWRITE=y plus ERRATA_THEAD_MAE=n; both errata options default to y, and an attacker cannot create this kernel configuration.\nPR:L - riscv_v_first_use_handler() and riscv_v_vstate_ctrl_set_current() contain no capability check, so an ordinary local user can enable vector state and execute the sequence; no administrative privilege or user namespace is required.\nUI:N - The attacking process itself enables or first-uses vector state and executes the faulty store; no victim must mount media, open a file, or perform another action.\nS:U - The missed disable_xtheadvector() call lets a user process escalate into the kernel on the same host; this is a local user-to-kernel privilege escalation under the host's existing security authority.\nC:H - Leaving xtheadvector enabled exposes GhostWrite's arbitrary physical-write primitive; overwriting a PTE's page-frame number creates an arbitrary physical-read mapping covering kernel and other-process memory.\nI:H - Because ghostwrite_enable_mitigation() returns false without the early VULNERABLE state, faulty high-order vector stores remain usable for attacker-chosen byte writes to physical memory, including PTEs and kernel or machine-mode code.\nA:H - The same unrestricted physical writes can corrupt kernel text, page tables, or device MMIO, causing an unrecoverable kernel crash or system hang."}]}],"providerMetadata":{"dateUpdated":"2026-10-24T14:10:04.808Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/fa465a7819ecbe5801b78c088d3cadaf2664b8ca"},{"url":"https://git.kernel.org/stable/c/7fee577a2fa78b9a76da015beec1ccf978746ebb"},{"url":"https://git.kernel.org/stable/c/298510bbc7c3017c0faf481c6ea66f1065b657b4"}],"title":"riscv: errata: select RISCV_ALTERNATIVE_EARLY for THEAD GHOSTWRITE","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-99017","datePublished":"2026-10-23T12:20:53.518Z","dateReserved":"2026-09-25T10:25:14.386Z","dateUpdated":"2026-10-24T14:10:04.808Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-10-23 13:17:24","lastModifiedDate":"2026-10-24 14:16:52","problem_types":[],"metrics":{"cvssMetricV31":[{"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7,"baseSeverity":"HIGH","attackVector":"LOCAL","attackComplexity":"HIGH","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"},"exploitabilityScore":1,"impactScore":5.9}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"99017","Ordinal":"1","Title":"riscv: errata: select RISCV_ALTERNATIVE_EARLY for THEAD GHOSTWRI","CVE":"CVE-2026-99017","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"99017","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nriscv: errata: select RISCV_ALTERNATIVE_EARLY for THEAD GHOSTWRITE\n\nerrata_probe_ghostwrite() only marks the CPU as vulnerable when it is\ncalled at the RISCV_ALTERNATIVES_EARLY_BOOT stage, and the mitigation\nin ghostwrite_enable_mitigation() only takes effect if the vulnerable\nstate was recorded before the boot alternatives are patched.\n\nThe early boot stage is only executed when CONFIG_RISCV_ALTERNATIVE_EARLY\nis enabled, which currently is only selected by ERRATA_THEAD_MAE. In a\nkernel built with ERRATA_THEAD_GHOSTWRITE=y but ERRATA_THEAD_MAE=n, the\nearly alternatives never run, so ghostwrite_state is never set to\nVULNERABLE: ghostwrite_enable_mitigation() returns false, xtheadvector\nremains enabled, and sysfs reports \"Not affected\" on a vulnerable\nT-Head C9xx CPU.\n\nSelect RISCV_ALTERNATIVE_EARLY from ERRATA_THEAD_GHOSTWRITE so that the\nvulnerability is detected in the early boot stage and the default\nmitigation is applied.","Type":"Description","Title":"riscv: errata: select RISCV_ALTERNATIVE_EARLY for THEAD GHOSTWRI"}]}}}