CVE-2021-47484

Kernel crash via null debugfs token dereference

Published May 22, 2024 · Updated May 11, 2026

NULL pointer dereference in Linux kernel 5.5 allows local users to crash the host through malformed OcteonTX2 AF debugfs input. In rvu_dbg_qsize_write(), a failed parse can leave subtoken null, but the original condition calls strncmp() on it before testing the parse error. The gate is low-privilege local access to a system using the affected driver; the bounded effect is loss of host availability, with no reported data exposure or modification.

CVSS severity5.5
Medium
EPSS probability0.18%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

NULL pointer dereference in Linux kernel 5.5 allows local users to crash the host through malformed OcteonTX2 AF debugfs input. In rvu_dbg_qsize_write(), a failed parse can leave subtoken null, but the original condition calls strncmp() on it before testing the parse error. The gate is low-privilege local access to a system using the affected driver; the bounded effect is loss of host availability, with no reported data exposure or modification.

The record

CVE
CVE-2021-47484
Published
May 22, 2024
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-476, T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 22, 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

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Is a vulnerable build present?

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

  1. Affected versionversion=5.5
  2. Affected versionversion=8756828a81485f7b28b588adbf0bac9bf6fc6651 <c2d4c543f74c90f883e8ec62a31973ae8807d354
  3. Affected versionversion=8756828a81485f7b28b588adbf0bac9bf6fc6651 <f1e3cd1cc80204fd02b9e9843450925a2af90dc0

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=5.5; version=8756828a81485f7b28b588adbf0bac9bf6fc6651 <c2d4c543f74c90f883e8ec62a31973ae8807d354; version=8756828a81485f7b28b588adbf0bac9bf6fc6651 <f1e3cd1cc80204fd02b9e9843450925a2af90dc0

Published CVSS scores

5.5CISA-ADPCVSS: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

CWE-476NULL Pointer Dereference
T1499.004Application or System Exploitation

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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