{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-99017", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-25T10:25:14.386Z", "datePublished": "2026-10-23T12:20:53.518Z", "dateUpdated": "2026-10-24T14:10:04.808Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-24T14:10:04.808Z" }, "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": { "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" }, "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." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "arch/riscv/Kconfig.errata" ], "versions": [ { "version": "4bf97069239bcfca9840936313c7ac35a6e04488", "lessThan": "fa465a7819ecbe5801b78c088d3cadaf2664b8ca", "status": "affected", "versionType": "git" }, { "version": "4bf97069239bcfca9840936313c7ac35a6e04488", "lessThan": "7fee577a2fa78b9a76da015beec1ccf978746ebb", "status": "affected", "versionType": "git" }, { "version": "4bf97069239bcfca9840936313c7ac35a6e04488", "lessThan": "298510bbc7c3017c0faf481c6ea66f1065b657b4", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "arch/riscv/Kconfig.errata" ], "versions": [ { "version": "6.14", "status": "affected" }, { "version": "0", "lessThan": "6.14", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.57", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2.11", "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": "6.14", "versionEndExcluding": "6.18.57" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.14", "versionEndExcluding": "7.2.11" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.14", "versionEndExcluding": "7.3" } ] } ] } ], "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" } } } }