CVE-2026-43385Network attack vector

RCU Tasks stall via repeated last_qs reset

Published May 8, 2026 · Updated May 8, 2026

Denial of service in Linux Kernel 6.19 through 6.19.8 allows remote attackers to stall RCU Tasks via threaded busypoll traffic. In net/core/dev.c, napi_threaded_poll_loop resets last_qs to current jiffies on each short invocation, preventing rcu_softirq_qs_periodic from reporting a quiescent state. Threaded busypoll must be enabled; the resulting grace-period stall can leave tracing tools such as bpftrace hanging.

CVSS severity7.5
High
EPSS probability0.34%
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 Linux Kernel 6.19 through 6.19.8 allows remote attackers to stall RCU Tasks via threaded busypoll traffic. In net/core/dev.c, napi_threaded_poll_loop resets last_qs to current jiffies on each short invocation, preventing rcu_softirq_qs_periodic from reporting a quiescent state. Threaded busypoll must be enabled; the resulting grace-period stall can leave tracing tools such as bpftrace hanging.

The record

CVE
CVE-2026-43385
Published
May 8, 2026
Updated
May 8, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 8, 2026CVE publishedPublication date reported by the CVE source.
  2. May 8, 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=6.19
  2. Affected versionversion=c18d4b190a46651726c9a952667c74d2deb33c28 <1a86a1f7d88996085934139fa4c063b6299a2dd3
  3. Affected versionversion=c18d4b190a46651726c9a952667c74d2deb33c28 <52459201d0df3fdbb1d281738b7b772e2cacb49c

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=6.19; version=c18d4b190a46651726c9a952667c74d2deb33c28 <1a86a1f7d88996085934139fa4c063b6299a2dd3; version=c18d4b190a46651726c9a952667c74d2deb33c28 <52459201d0df3fdbb1d281738b7b772e2cacb49c

Published CVSS scores

7.5kernel.orgCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
6.8UbuntuCVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
7.5UbuntuCVSS:3.1/AV:N/AC:L/PR:N/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)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

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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