CVE-2021-47422

Local denial of service via unreleased debugfs allocations

Published May 21, 2024 · Updated May 11, 2026

Memory leak in the Linux Nouveau NV50 CRC debugfs interface allows local users to exhaust kernel memory by repeatedly opening its file. The nv50_crc_flip_threshold file operations call single_open() but omit single_release(), leaving the private seq_file allocation unreclaimed after close. Exploitation requires local low-privileged access, an active Nouveau NV50 display path, and mounted debugfs; repeated opens can interrupt service without reading or altering data.

CVSS severity5.5
Medium
EPSS probability0.22%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Memory leak in the Linux Nouveau NV50 CRC debugfs interface allows local users to exhaust kernel memory by repeatedly opening its file. The nv50_crc_flip_threshold file operations call single_open() but omit single_release(), leaving the private seq_file allocation unreclaimed after close. Exploitation requires local low-privileged access, an active Nouveau NV50 display path, and mounted debugfs; repeated opens can interrupt service without reading or altering data.

The record

CVE
CVE-2021-47422
Published
May 21, 2024
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-401, T1499.004
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=12885ecbfe62df4358d452080d3b8feef54ec8cb <0b3d4945cc7e7ea1acd52cb06dfa83bfe265b6d5
  2. Affected versionversion=12885ecbfe62df4358d452080d3b8feef54ec8cb <0b4e9fc14973a94ac0520f19b3633493ae13c912
  3. Affected versionversion=12885ecbfe62df4358d452080d3b8feef54ec8cb <65fff0a8efcdca8d84ffe3e23057c3b32403482d
  4. Affected versionversion=5.9

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=12885ecbfe62df4358d452080d3b8feef54ec8cb <0b3d4945cc7e7ea1acd52cb06dfa83bfe265b6d5; version=12885ecbfe62df4358d452080d3b8feef54ec8cb <0b4e9fc14973a94ac0520f19b3633493ae13c912; version=12885ecbfe62df4358d452080d3b8feef54ec8cb <65fff0a8efcdca8d84ffe3e23057c3b32403482d; version=5.9

Published CVSS scores

5.5NIST National Vulnerability DatabaseCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
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

CWE-401Missing Release of Memory after Effective Lifetime
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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