PT-2024-11234 · Linux+1 · Linux Kernel+1

Published 2021-06-09 · Updated 2024-05-21 · CVE-2021-47226

Positive Technologies (AI Summary)

CVSS v3.1

7.1

High

Base vector

AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H

Name of the Vulnerable Software and Affected Versions Linux kernel (affected versions not specified)

Description The issue arises when the XRSTOR instruction fails with a #PF exception but still modifies the register state, which is considered architecturally valid by both Intel and AMD. This might occur when one sibling thread unmaps a page and invalidates the shared TLB while another sibling thread is executing XRSTOR on the same page. The fpu restore sig() function can execute XRSTOR with preserved hardware registers on behalf of a different victim task, potentially leading to a situation where the victim task's user-visible state is corrupted if fpu restore sig() schedules out and the victim task schedules back in without reloading its own FPU registers. To prevent this, preserved FPU registers are invalidated on XRSTOR failure.

Recommendations At the moment, there is no information about a newer version that contains a fix for this vulnerability.

Side Channel Attack

Weakness Enumeration

CWE-402

CWE-203

Related Identifiers

BDU:2025-13717

CVE-2021-47226

Affected Products

Astra Linux

Linux Kernel

References · 16

• https://osv.dev/vulnerability/CVE-2021-47226 · Vendor Advisory
• https://osv.dev/vulnerability/DEBIAN-CVE-2021-47226 · Vendor Advisory
• https://ubuntu.com/security/CVE-2021-47226 · Vendor Advisory
• https://git.kernel.org/stable/c/a7748e021b9fb7739e3cb88449296539de0b6817 · Patch
• https://security-tracker.debian.org/tracker/CVE-2021-47226 · Vendor Advisory
• https://osv.dev/vulnerability/UBUNTU-CVE-2021-47226 · Vendor Advisory
• https://git.kernel.org/stable/c/002665dcba4bbec8c82f0aeb4bd3f44334ed2c14 · Patch
• https://bdu.fstec.ru/vul/2025-13717 · Security Note
• https://cve.org/CVERecord?id=CVE-2021-47226 · Security Note
• https://nvd.nist.gov/vuln/detail/CVE-2021-47226 · Security Note
• https://git.kernel.org/stable/c/d8778e393afa421f1f117471144f8ce6deb6953a · Patch
• https://git.kernel.org/linus/d8778e393afa421f1f117471144f8ce6deb6953a · Note
• https://kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.10.46 · Note
• https://lore.kernel.org/linux-cve-announce/2024052137-CVE-2021-47226-5d4f@gregkh · Note
• https://git.linuxtesting.ru/pub/scm/linux/kernel/git/lvc/linux-stable.git/commit/?h=v5.10.176-lvc1&id=a7748e021b9fb7739e3cb88449296539de0b6817 · Note