CVE-2021-46956

Local service interruption via duplicate virtiofs tags

Published Feb 27, 2024 · Updated May 11, 2026

Memory leak in Linux virtiofs allows local users to consume unreleased kernel memory by configuring duplicate QEMU filesystem tags. In virtio_fs_probe(), the duplicate-tag error path frees fs but leaves the allocated fs->vqs queue array unreleased. The user must be able to configure a virtiofs device in QEMU; repeated failed probes consume memory and can interrupt service.

CVSS severity5.5
Medium
EPSS probability0.23%
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 Linux virtiofs allows local users to consume unreleased kernel memory by configuring duplicate QEMU filesystem tags. In virtio_fs_probe(), the duplicate-tag error path frees fs but leaves the allocated fs->vqs queue array unreleased. The user must be able to configure a virtiofs device in QEMU; repeated failed probes consume memory and can interrupt service.

The record

CVE
CVE-2021-46956
Published
Feb 27, 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. Feb 27, 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=5.4
  2. Affected versionversion=a62a8ef9d97da23762a588592c8b8eb50a8deb6a <310efc95c72c13faf855c692d19cd4d054d827c8
  3. Affected versionversion=a62a8ef9d97da23762a588592c8b8eb50a8deb6a <5116e79fc6e6725b8acdad8b7e928a83ab7b47e6
  4. Affected versionversion=a62a8ef9d97da23762a588592c8b8eb50a8deb6a <9b9d60c0eb8ada99cce2a9ab5c15dffc523b01ae
  5. Affected versionversion=a62a8ef9d97da23762a588592c8b8eb50a8deb6a <c79c5e0178922a9e092ec8fed026750f39dcaef4
  6. Affected versionversion=a62a8ef9d97da23762a588592c8b8eb50a8deb6a <d19555ff225d0896a33246a49279e6d578095f15

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=5.4; version=a62a8ef9d97da23762a588592c8b8eb50a8deb6a <310efc95c72c13faf855c692d19cd4d054d827c8; version=a62a8ef9d97da23762a588592c8b8eb50a8deb6a <5116e79fc6e6725b8acdad8b7e928a83ab7b47e6; version=a62a8ef9d97da23762a588592c8b8eb50a8deb6a <9b9d60c0eb8ada99cce2a9ab5c15dffc523b01ae; version=a62a8ef9d97da23762a588592c8b8eb50a8deb6a <c79c5e0178922a9e092ec8fed026750f39dcaef4; version=a62a8ef9d97da23762a588592c8b8eb50a8deb6a <d19555ff225d0896a33246a49279e6d578095f15

Published CVSS scores

4.7Amazon LinuxCVSS:3.1/AV:L/AC:H/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.

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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
T1499.004Endpoint Denial of Service: Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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