CVE-2021-47035

Device mapping failure via write-only entries

Published Feb 28, 2024 · Updated Aug 5, 2026

Improper permission handling in the Linux kernel's Intel VT-d IOMMU allows local users to cause device-mapping failures. __domain_mapping copies write permission into second-level page-table entries without also setting the PRESENT bit, accepting a write-only mapping that first-level translation cannot represent. The path requires Intel VT-d hardware and a local mapping operation; public sources report availability impact but do not identify a specific crash or hang mode.

CVSS severity5.5
Medium
EPSS probability0.26%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper permission handling in the Linux kernel's Intel VT-d IOMMU allows local users to cause device-mapping failures. __domain_mapping copies write permission into second-level page-table entries without also setting the PRESENT bit, accepting a write-only mapping that first-level translation cannot represent. The path requires Intel VT-d hardware and a local mapping operation; public sources report availability impact but do not identify a specific crash or hang mode.

The record

CVE
CVE-2021-47035
Published
Feb 28, 2024
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 28, 2024CVE publishedPublication date reported by the CVE source.
  2. Aug 5, 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=5.6
  2. Affected versionversion=b802d070a52a1565b47daaa808872cfbd4a17b01 <25faff78138933244c678c7fc78f7c0340fa04a0
  3. Affected versionversion=b802d070a52a1565b47daaa808872cfbd4a17b01 <66c24699f266ff310381a9552d3576eea8ad6e20
  4. Affected versionversion=b802d070a52a1565b47daaa808872cfbd4a17b01 <89bd620798704a8805fc9db0d71d7f812cf5b3d2
  5. Affected versionversion=b802d070a52a1565b47daaa808872cfbd4a17b01 <eea53c5816889ee8b64544fa2e9311a81184ff9c

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=5.6; version=b802d070a52a1565b47daaa808872cfbd4a17b01 <25faff78138933244c678c7fc78f7c0340fa04a0; version=b802d070a52a1565b47daaa808872cfbd4a17b01 <66c24699f266ff310381a9552d3576eea8ad6e20; version=b802d070a52a1565b47daaa808872cfbd4a17b01 <89bd620798704a8805fc9db0d71d7f812cf5b3d2; version=b802d070a52a1565b47daaa808872cfbd4a17b01 <eea53c5816889ee8b64544fa2e9311a81184ff9c

Published CVSS scores

6.0Amazon LinuxCVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:N
5.5UbuntuCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
5.5NIST NVDCVSS: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

T1499Endpoint Denial of Service

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

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Your stack

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