CVE-2019-20812

CPU soft lockup via zero retire timeout

Published Jun 3, 2020 · Updated Aug 5, 2024

Denial of service in the Linux kernel before 5.4.7 allows local users with CAP_NET_RAW to cause a CPU soft lockup through TPACKET_V3. If __ethtool_get_link_ksettings() fails, prb_calc_retire_blk_tmo() leaves the timeout at zero and repeatedly schedules retire_blk_timer at the current jiffy, driving softirq CPU use to 100%. Triggering the failure path requires CAP_NET_RAW; successful exploitation hangs a CPU in softirq processing without reading or changing data.

CVSS severity5.5
Medium
EPSS probability0.44%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in the Linux kernel before 5.4.7 allows local users with CAP_NET_RAW to cause a CPU soft lockup through TPACKET_V3. If __ethtool_get_link_ksettings() fails, prb_calc_retire_blk_tmo() leaves the timeout at zero and repeatedly schedules retire_blk_timer at the current jiffy, driving softirq CPU use to 100%. Triggering the failure path requires CAP_NET_RAW; successful exploitation hangs a CPU in softirq processing without reading or changing data.

The record

CVE
CVE-2019-20812
Published
Jun 3, 2020
Updated
Aug 5, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-400, T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jun 3, 2020CVE publishedPublication date reported by the CVE source.
  2. Aug 5, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

4.9NIST NVDAV:L/AC:L/Au:N/C:N/I:N/A:C
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-400Uncontrolled Resource Consumption
T1499.004Application 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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