CVE-2026-43029
published 2026-05-01CVE-2026-43029: 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()…
PriorityP342high7.5CVSS 3.1
AVNACLPRNUINSUCNINAH
EPSS
0.33%
25.5th percentile
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 83 ec 30 65 48 8b 05 17 a4 6b 01 48 89 44 24 28 31 c0 65 48 8b
RSP: 0018:ffffc90000603ca0 EFLAGS: 00000246
RAX: 0000000000000000 RBX: ffff888102bf0800 RCX: 0000000000000001
RDX: 0000000000000000 RSI: ffffc90000603d18 RDI: ffff888102bf0800
RBP: 0000000000000000 R08: 0000000000000002 R09: 0000000000000101
R10: 0000000000000000 R11: 0000000000000075 R12: ffffc90000603d18
R13: ffff888102bf0800 R14: ffff888102bf0800 R15: 0000000000000000
FS: 00007f6e38b8c4c0(0000) GS:ffff8881b877e000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055aa7bff1680 CR3: 0000000105cbe000 CR4: 00000000000006f0
Call Trace:
mptcp_recvmsg+0x547/0x8c0 net/mptcp/protocol.c:2329
inet_recvmsg+0x11f/0x130 net/ipv4/af_inet.c:891
sock_recvmsg+0x94/0xc0 net/socket.c:1100
__sys_recvfrom+0xb2/0x130 net/socket.c:2256
__x64_sys_recvfrom+0x1f/0x30 net/socket.c:2267
do_syscall_64+0x59/0x2d0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x76/0x7e arch/x86/entry/entry_64.S:131
RIP: 0033:0x7f6e
Affected
18 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| linux | linux | — | — |
| linux | linux | — | — |
| linux | linux | — | — |
| linux | linux | — | — |
| linux | linux | >= 6.12.59 < 6.13 | 6.13 |
| linux | linux | >= 6.17.8 < 6.18 | 6.18 |
| linux | linux | >= 6.6.117 < 6.7 | 6.7 |
| linux | linux | >= 8e04ce45a8db7a080220e86e249198fa676b83dc < 58b58b9ba89c43914eea90c18928e51852d10c24 | 58b58b9ba89c43914eea90c18928e51852d10c24 |
| linux | linux | >= 8e04ce45a8db7a080220e86e249198fa676b83dc < de3c248d1b69eaefa2d5b3da4005936dcf590f1b | de3c248d1b69eaefa2d5b3da4005936dcf590f1b |
| linux | linux | >= 8e04ce45a8db7a080220e86e249198fa676b83dc < 5dd8025a49c268ab6b94d978532af3ad341132a7 | 5dd8025a49c268ab6b94d978532af3ad341132a7 |
| linux | linux_kernel | — | — |
| linux | linux_kernel | — | — |
| linux | linux_kernel | — | — |
| linux | linux_kernel | — | — |
| linux | linux_kernel | — | — |
| linux | linux_kernel | — | — |
| linux | linux_kernel | >= 6.18.1 < 6.18.22 | 6.18.22 |
| linux | linux_kernel | >= 6.19 < 6.19.12 | 6.19.12 |
CVSS provenance
nvdv3.17.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
vendor_redhat7.0MEDIUM
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Red Hat
kernel: mptcp: fix soft lockup in mptcp_recvmsg()
vendor_redhat·2026-05-01·CVSS 7.0
CVE-2026-43029 [MEDIUM] CWE-606 kernel: mptcp: fix soft lockup in mptcp_recvmsg()
kernel: mptcp: fix soft lockup in mptcp_recvmsg()
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.
Package: kernel (Red Hat Enterprise Linux 10) - Affected
Package: kernel (Red Hat Enterprise Linux 6) - Not affected
Package: kernel (Red Hat Enterprise Linux 7) - Not affected
Package: kernel-rt (Red Hat Enterprise Linux 7) - Not affected
Package: kernel (Red Hat Enterprise Linux 8) - Not affected
Package: kernel-
VulDB
Linux Kernel up to 6.18.21/6.19.11 mptcp mptcp_recvmsg infinite loop
vuldb·2026-05-01
CVE-2026-43029 [CRITICAL] Linux Kernel up to 6.18.21/6.19.11 mptcp mptcp_recvmsg infinite loop
A vulnerability, which was classified as critical, has been found in Linux Kernel up to 6.18.21/6.19.11. The impacted element is the function mptcp_recvmsg of the component mptcp. This manipulation causes infinite loop.
This vulnerability is tracked as CVE-2026-43029. The attack is only possible within the local network. No exploit exists.
It is advisable to upgrade the affected component.
GHSA
GHSA-fc34-92xq-43pm: In the Linux kernel, the following vulnerability has been resolved:
mptcp: fix soft lockup in mptcp_recvmsg()
syzbot reported a soft lockup in mptcp
ghsa_unreviewed·2026-05-01
CVE-2026-43029 [HIGH] GHSA-fc34-92xq-43pm: In the Linux kernel, the following vulnerability has been resolved:
mptcp: fix soft lockup in mptcp_recvmsg()
syzbot reported a soft lockup in mptcp
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.
No detection rules found.
No public exploits indexed.
2026-05-01
Published