CVE-2026-43029

Technical Description

In the Linux kernel, the following vulnerability has been resolved:

mptcp: fix soft lockup in mptcp_recvmsg()

syzbot reported a soft lockup in mptcp_recvmsg() [0].

When receiving data with MSG_PEEK | MSG_WAITALL flags, the skb is not

removed from the sk_receive_queue. This causes sk_wait_data() to always

find available data and never perform actual waiting, leading to a soft

lockup.

Fix this by adding a 'last' parameter to track the last peeked skb.

This allows sk_wait_data() to make informed waiting decisions and prevent

infinite loops when MSG_PEEK is used.

[0]:

watchdog: BUG: soft lockup - CPU#2 stuck for 156s! [server:1963]

Modules linked in:

CPU: 2 UID: 0 PID: 1963 Comm: server Not tainted 6.19.0-rc8 #61 PREEMPT(none)

Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014

RIP: 0010:sk_wait_data+0x15/0x190

Code: 80 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 41 56 41 55 41 54 49 89 f4 55 48 89 d5 53 48 89 fb <48> 83 ec 30 65

Remediation

Check the references section for vendor advisories and patches from linux. Update linux_kernel to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

Affected Products

References