CVE-2026-43029

Description

A flaw was found in the Linux kernel's Multipath TCP (mptcp) implementation. When an attacker sends data with MSG_PEEK | MSG_WAITALL flags, the system can enter a soft lockup state. This occurs because the sk_receive_queue is not properly cleared, causing the system to continuously find available data without actual waiting. This vulnerability can lead to a Denial of Service (DoS) condition, making the system unresponsive.

Statement

MPTCP recvmsg could soft-lockup under certain scheduling conditions; upstream fixes progress checks. Red Hat advises MPTCP users to update; optionally unload mptcp where the protocol is unused.

Mitigation

To mitigate this issue, prevent the mptcp module from being loaded. See https://access.redhat.com/solutions/41278 for instructions.

Common Vulnerability Scoring System (CVSS) Score Details

Info alert:Important note

CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).

The following CVSS metrics and score provided are preliminary and subject to review.

CVSS v3 Score Breakdown

Red HatNVDcve.org
Base Score5.5N/A7.5
Attack VectorLocalN/ANetwork
Attack ComplexityLowN/ALow
Privileges RequiredLowN/ANone
User InteractionNoneN/ANone
ScopeUnchangedN/AUnchanged
ConfidentialityNoneN/ANone
Integrity ImpactNoneN/ANone
Availability ImpactHighN/AHigh

Vector

Red Hat: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Understanding the Weakness (CWE)

CWE-606

Availability

Technical Impact: DoS: Resource Consumption (CPU)

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