CVE-2021-32846Public exploit

Host crash via unchecked negative descriptor count

Published Feb 17, 2023 · Updated Mar 10, 2025

Uninitialized memory use in HyperKit 0.20210107 allows guest OS users to crash the host or corrupt host memory through a malformed virtio-sock queue. In pci_vtsock_proc_tx, vq_getchain can return -1, but the code accepts it and passes the negative iovec length into iovec_pull, which walks uninitialized vector entries. A malicious guest must submit the malformed transmit virtqueue; the demonstrated consequence is a host crash, while the advisory also reports possible host-memory corruption.

CVSS severity7.7
High
EPSS probability0.32%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Uninitialized memory use in HyperKit 0.20210107 allows guest OS users to crash the host or corrupt host memory through a malformed virtio-sock queue. In pci_vtsock_proc_tx, vq_getchain can return -1, but the code accepts it and passes the negative iovec length into iovec_pull, which walks uninitialized vector entries. A malicious guest must submit the malformed transmit virtqueue; the demonstrated consequence is a host crash, while the advisory also reports possible host-memory corruption.

The record

CVE
CVE-2021-32846
Published
Feb 17, 2023
Updated
Mar 10, 2025
Vendor
Moby Project
Product
HyperKit
Classifications
CWE-754, CWE-908, T1499.004
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 17, 2023CVE publishedPublication date reported by the CVE source.
  2. Mar 10, 2025Record 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=0.20210107 <=0.20210107

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Moby Project · HyperKitversion=0.20210107 <=0.20210107

Published CVSS scores

7.7GitHub, Inc.CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H
7.8NISTCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-754Improper Check for Unusual or Exceptional Conditions
CWE-908Use of Uninitialized Resource
T1499.004Application or System Exploitation

Public exploit references

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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