CVE-2021-47227

Local service interruption via unchecked XSAVE header

Published May 21, 2024 · Updated May 11, 2026

Improper input validation in Linux allows local users to interrupt service by restoring a crafted x86 FPU signal frame. The non-compacted __fpu__restore_sig() slow path copies the entire user buffer into the kernel XSAVE buffer without validating its header before XRSTOR consumes it. Reachability requires local low-privileged code on an affected x86 kernel, and invalid state can trigger a general-protection fault that interrupts normal operation.

CVSS severity5.5
Medium
EPSS probability0.24%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper input validation in Linux allows local users to interrupt service by restoring a crafted x86 FPU signal frame. The non-compacted __fpu__restore_sig() slow path copies the entire user buffer into the kernel XSAVE buffer without validating its header before XRSTOR consumes it. Reachability requires local low-privileged code on an affected x86 kernel, and invalid state can trigger a general-protection fault that interrupts normal operation.

The record

CVE
CVE-2021-47227
Published
May 21, 2024
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
Unavailable
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 21, 2024CVE publishedPublication date reported by the CVE source.
  2. May 11, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=5.8
  2. Affected versionversion=b860eb8dce5906b14e3a7f3c771e0b3d6ef61b94 <076f732b16a5bf842686e1b43ab6021a2d98233e
  3. Affected versionversion=b860eb8dce5906b14e3a7f3c771e0b3d6ef61b94 <484cea4f362e1eeb5c869abbfb5f90eae6421b38
  4. Affected versionversion=b860eb8dce5906b14e3a7f3c771e0b3d6ef61b94 <ec25ea1f3f05d6f8ee51d1277efea986eafd4f2a

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=5.8; version=b860eb8dce5906b14e3a7f3c771e0b3d6ef61b94 <076f732b16a5bf842686e1b43ab6021a2d98233e; version=b860eb8dce5906b14e3a7f3c771e0b3d6ef61b94 <484cea4f362e1eeb5c869abbfb5f90eae6421b38; version=b860eb8dce5906b14e3a7f3c771e0b3d6ef61b94 <ec25ea1f3f05d6f8ee51d1277efea986eafd4f2a

Published CVSS scores

5.5Canonical UbuntuCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

No sourced classifications are available.

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

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