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Review reviewHigh

CVE-2021-47226

Linux Linux, linux kernel

In the Linux kernel, the following vulnerability has been resolved: x86/fpu: Invalidate FPU state after a failed XRSTOR from a user buffer Both Intel and AMD consider it to be architecturally valid for XRSTOR to fail with #PF but nonetheless change the register state. The actual conditions under which this might occur are unclear [1], but it seems plausible that this might be triggered if one sibling thread unmaps a page and invalidates the shared TLB while another sibling thread is executing XRSTOR on the page in question. __fpu__restore_sig() can execute XRSTOR while the hardware register...

CVSS
7.1
EPSS
0.22%
12.9% percentile
CISA KEV
Not listed
Published
2024.05.22
PRIORITY ASSESSMENT

Review review

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV
Exploit probability0.22%
Technical severityCVSS 7.1

Vulnerability overview

In the Linux kernel, the following vulnerability has been resolved: x86/fpu: Invalidate FPU state after a failed XRSTOR from a user buffer Both Intel and AMD consider it to be architecturally valid for XRSTOR to fail with #PF but nonetheless change the register state. The actual conditions under which this might occur are unclear [1], but it seems plausible that this might be triggered if one sibling thread unmaps a page and invalidates the shared TLB while another sibling thread is executing XRSTOR on the page in question. __fpu__restore_sig() can execute XRSTOR while the hardware register...

Affected product and versions

Product
Linux Linux, linux kernel
Affected versions
>= 1d731e731c4cd7cbd3b1aa295f0932e7610da82f < a7748e021b9fb7739e3cb88449296539de0b6817, >= 1d731e731c4cd7cbd3b1aa295f0932e7610da82f < 002665dcba4bbec8c82f0aeb4bd3f44334ed2c14, >= 1d731e731c4cd7cbd3b1aa295f0932e7610da82f < d8778e393afa421f1f117471144f8ce6deb6953a, >= 5.2, >= 5.2 < 5.10.46, >= 5.11 < 5.12.13, 5.13
Fixed versions
5.10.46, 5.12.13

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide
  1. 1
    Identify

    Confirm that Linux Linux, linux kernel and an affected version are present.

  2. 2
    Prioritize

    Combine exploitation signals with asset exposure and business criticality.

  3. 3
    Remediate

    Follow the vendor advisory or supported update path and preserve rollback options.

  4. 4
    Verify

    Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H
CWE
CWE-203
CVE-2021-47226 — Linux Linux, linux kernel | SECUFOCUS NOW