CVE-2026-43029Network attack vector

Remote soft lockup via MPTCP receive loop

Published May 1, 2026 · Updated May 1, 2026

Denial of service in the Linux Kernel allows remote attackers to cause a soft lockup through crafted MPTCP traffic. In mptcp_recvmsg(), MSG_PEEK with MSG_WAITALL leaves the same skb on sk_receive_queue, so sk_wait_data() repeatedly sees data and never waits. Reachability requires a network-facing MPTCP service that performs the blocking peek receive; an unauthenticated peer can keep a CPU stuck by supplying only partial data.

CVSS severity7.5
High
EPSS probability0.33%
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 allows remote attackers to cause a soft lockup through crafted MPTCP traffic. In mptcp_recvmsg(), MSG_PEEK with MSG_WAITALL leaves the same skb on sk_receive_queue, so sk_wait_data() repeatedly sees data and never waits. Reachability requires a network-facing MPTCP service that performs the blocking peek receive; an unauthenticated peer can keep a CPU stuck by supplying only partial data.

The record

CVE
CVE-2026-43029
Published
May 1, 2026
Updated
May 1, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-667, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 1, 2026CVE publishedPublication date reported by the CVE source.
  2. May 1, 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=0206a9341e652167c610dcd79f3d4e9e8153984c
  2. Affected versionversion=49888b3b457b801282b44c246d289c56e2f2a55b
  3. Affected versionversion=6.18
  4. Affected versionversion=7d6d10eee01edc9c20850ea75cf8273dc1170921
  5. Affected versionversion=8e04ce45a8db7a080220e86e249198fa676b83dc <58b58b9ba89c43914eea90c18928e51852d10c24
  6. Affected versionversion=8e04ce45a8db7a080220e86e249198fa676b83dc <5dd8025a49c268ab6b94d978532af3ad341132a7
  7. Affected versionversion=8e04ce45a8db7a080220e86e249198fa676b83dc <de3c248d1b69eaefa2d5b3da4005936dcf590f1b

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=0206a9341e652167c610dcd79f3d4e9e8153984c; version=49888b3b457b801282b44c246d289c56e2f2a55b; version=6.18; version=7d6d10eee01edc9c20850ea75cf8273dc1170921; version=8e04ce45a8db7a080220e86e249198fa676b83dc <58b58b9ba89c43914eea90c18928e51852d10c24; version=8e04ce45a8db7a080220e86e249198fa676b83dc <5dd8025a49c268ab6b94d978532af3ad341132a7; version=8e04ce45a8db7a080220e86e249198fa676b83dc <de3c248d1b69eaefa2d5b3da4005936dcf590f1b

Published CVSS scores

7.5kernel.orgCVSS: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

CWE-667Improper Locking
T1499Endpoint Denial of Service

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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