{"cve":"CVE-2021-47226","nvd":{"published":"2024-05-21T15:15:11.823","modified":"2026-08-04T10:16:53.647","status":"Modified","description":"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\".","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H","score":7.1},"cwes":["CWE-203"],"references":["https://git.kernel.org/stable/c/002665dcba4bbec8c82f0aeb4bd3f44334ed2c14","https://git.kernel.org/stable/c/a7748e021b9fb7739e3cb88449296539de0b6817","https://git.kernel.org/stable/c/d8778e393afa421f1f117471144f8ce6deb6953a","https://git.kernel.org/stable/c/002665dcba4bbec8c82f0aeb4bd3f44334ed2c14","https://git.kernel.org/stable/c/a7748e021b9fb7739e3cb88449296539de0b6817"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-19T21:50:30.954589733+00:00"},"epss":{"cve":"CVE-2021-47226","score":0.00224,"percentile":0.13096,"date":"2026-10-31"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}