{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2021-47226", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2024-04-10T18:59:19.529Z", "datePublished": "2024-05-21T14:19:30.864Z", "dateUpdated": "2026-08-05T08:46:49.937Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T08:46:49.937Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nx86/fpu: Invalidate FPU state after a failed XRSTOR from a user buffer\n\nBoth Intel and AMD consider it to be architecturally valid for XRSTOR to\nfail with #PF but nonetheless change the register state. The actual\nconditions under which this might occur are unclear [1], but it seems\nplausible that this might be triggered if one sibling thread unmaps a page\nand invalidates the shared TLB while another sibling thread is executing\nXRSTOR on the page in question.\n\n__fpu__restore_sig() can execute XRSTOR while the hardware registers\nare preserved on behalf of a different victim task (using the\nfpu_fpregs_owner_ctx mechanism), and, in theory, XRSTOR could fail but\nmodify the registers.\n\nIf this happens, then there is a window in which __fpu__restore_sig()\ncould schedule out and the victim task could schedule back in without\nreloading its own FPU registers. This would result in part of the FPU\nstate that __fpu__restore_sig() was attempting to load leaking into the\nvictim task's user-visible state.\n\nInvalidate preserved FPU registers on XRSTOR failure to prevent this\nsituation from corrupting any state.\n\n[1] Frequent readers of the errata lists might imagine \"complex\n microarchitectural conditions\"." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H", "baseScore": 7.1, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:L - The vulnerable path is reached only via the local rt_sigreturn/sigreturn syscalls into __fpu__restore_sig(); it cannot be triggered by network packets or remote protocols.\nAC:L - An unprivileged attacker can reliably set up both sides of the race (one thread performing sigreturn XRSTOR while a sibling unmaps the buffer/TLB) and retry until the architecturally allowed partial XRSTOR-on-#PF occurs.\nPR:L - Any unprivileged local user can invoke rt_sigreturn and supply a crafted signal frame; no capabilities or root privileges are required.\nUI:N - Exploitation requires only the attacker's own threads and normal scheduling alongside other tasks; no separate victim user action is needed.\nS:U - Impact stays within the kernel's process-management authority (cross-task FPU register corruption on the same OS); this is not a VM/hypervisor or IOMMU boundary escape.\nC:N - The flaw injects attacker-controlled FPU/SIMD state into another task's registers; it does not provide a primitive for the attacker to read victim or kernel memory.\nI:H - Failed XRSTOR can write attacker-chosen user xstate (FP/SSE/AVX and related features) into hardware registers still attributed to a victim task, which then resumes with corrupted, attacker-influenced register state.\nA:H - Corrupting another task's FPU/MXCSR/SIMD state can cause that process to fault, abort, or otherwise fail, enabling cross-process denial of service." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "arch/x86/kernel/fpu/signal.c" ], "versions": [ { "version": "1d731e731c4cd7cbd3b1aa295f0932e7610da82f", "lessThan": "a7748e021b9fb7739e3cb88449296539de0b6817", "status": "affected", "versionType": "git" }, { "version": "1d731e731c4cd7cbd3b1aa295f0932e7610da82f", "lessThan": "002665dcba4bbec8c82f0aeb4bd3f44334ed2c14", "status": "affected", "versionType": "git" }, { "version": "1d731e731c4cd7cbd3b1aa295f0932e7610da82f", "lessThan": "d8778e393afa421f1f117471144f8ce6deb6953a", "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/x86/kernel/fpu/signal.c" ], "versions": [ { "version": "5.2", "status": "affected" }, { "version": "0", "lessThan": "5.2", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.46", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.12.13", "lessThanOrEqual": "5.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.13", "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": "5.2", "versionEndExcluding": "5.10.46" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.2", "versionEndExcluding": "5.12.13" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.2", "versionEndExcluding": "5.13" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/a7748e021b9fb7739e3cb88449296539de0b6817" }, { "url": "https://git.kernel.org/stable/c/002665dcba4bbec8c82f0aeb4bd3f44334ed2c14" }, { "url": "https://git.kernel.org/stable/c/d8778e393afa421f1f117471144f8ce6deb6953a" } ], "title": "x86/fpu: Invalidate FPU state after a failed XRSTOR from a user buffer", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "title": "CISA ADP Vulnrichment", "metrics": [ { "other": { "type": "ssvc", "content": { "id": "CVE-2021-47226", "role": "CISA Coordinator", "options": [ { "Exploitation": "none" }, { "Automatable": "no" }, { "Technical Impact": "partial" } ], "version": "2.0.3", "timestamp": "2024-05-21T15:36:03.024870Z" } } } ], "providerMetadata": { "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2024-06-04T17:15:21.177Z" } }, { "providerMetadata": { "orgId": "af854a3a-2127-422b-91ae-364da2661108", "shortName": "CVE", "dateUpdated": "2024-08-04T05:32:07.454Z" }, "title": "CVE Program Container", "references": [ { "url": "https://git.kernel.org/stable/c/a7748e021b9fb7739e3cb88449296539de0b6817", "tags": [ "x_transferred" ] }, { "url": "https://git.kernel.org/stable/c/002665dcba4bbec8c82f0aeb4bd3f44334ed2c14", "tags": [ "x_transferred" ] }, { "url": "https://git.kernel.org/stable/c/d8778e393afa421f1f117471144f8ce6deb6953a", "tags": [ "x_transferred" ] } ] } ] } }