CVE-2026-43164 - Vulnerability Details

- udplite: Fix null-ptr-deref in __udp_enqueue_schedule_skb().

Description

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

udplite: Fix null-ptr-deref in __udp_enqueue_schedule_skb().

syzbot reported null-ptr-deref of udp_sk(sk)->udp_prod_queue. [0]

Since the cited commit, udp_lib_init_sock() can fail, as can
udp_init_sock() and udpv6_init_sock().

Let's handle the error in udplite_sk_init() and udplitev6_sk_init().

[0]:
BUG: KASAN: null-ptr-deref in instrument_atomic_read include/linux/instrumented.h:82 [inline]
BUG: KASAN: null-ptr-deref in atomic_read include/linux/atomic/atomic-instrumented.h:32 [inline]
BUG: KASAN: null-ptr-deref in __udp_enqueue_schedule_skb+0x151/0x1480 net/ipv4/udp.c:1719
Read of size 4 at addr 0000000000000008 by task syz.2.18/2944

CPU: 1 UID: 0 PID: 2944 Comm: syz.2.18 Not tainted syzkaller #0 PREEMPTLAZY
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
<IRQ>
dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
kasan_report+0xa2/0xe0 mm/kasan/report.c:595
check_region_inline mm/kasan/generic.c:-1 [inline]
kasan_check_range+0x264/0x2c0 mm/kasan/generic.c:200
instrument_atomic_read include/linux/instrumented.h:82 [inline]
atomic_read include/linux/atomic/atomic-instrumented.h:32 [inline]
__udp_enqueue_schedule_skb+0x151/0x1480 net/ipv4/udp.c:1719
__udpv6_queue_rcv_skb net/ipv6/udp.c:795 [inline]
udpv6_queue_rcv_one_skb+0xa2e/0x1ad0 net/ipv6/udp.c:906
udp6_unicast_rcv_skb+0x227/0x380 net/ipv6/udp.c:1064
ip6_protocol_deliver_rcu+0xe17/0x1540 net/ipv6/ip6_input.c:438
ip6_input_finish+0x191/0x350 net/ipv6/ip6_input.c:489
NF_HOOK+0x354/0x3f0 include/linux/netfilter.h:318
ip6_input+0x16c/0x2b0 net/ipv6/ip6_input.c:500
NF_HOOK+0x354/0x3f0 include/linux/netfilter.h:318
__netif_receive_skb_one_core net/core/dev.c:6149 [inline]
__netif_receive_skb+0xd3/0x370 net/core/dev.c:6262
process_backlog+0x4d6/0x1160 net/core/dev.c:6614
__napi_poll+0xae/0x320 net/core/dev.c:7678
napi_poll net/core/dev.c:7741 [inline]
net_rx_action+0x60d/0xdc0 net/core/dev.c:7893
handle_softirqs+0x209/0x8d0 kernel/softirq.c:622
do_softirq+0x52/0x90 kernel/softirq.c:523
</IRQ>
<TASK>
__local_bh_enable_ip+0xe7/0x120 kernel/softirq.c:450
local_bh_enable include/linux/bottom_half.h:33 [inline]
rcu_read_unlock_bh include/linux/rcupdate.h:924 [inline]
__dev_queue_xmit+0x109c/0x2dc0 net/core/dev.c:4856
__ip6_finish_output net/ipv6/ip6_output.c:-1 [inline]
ip6_finish_output+0x158/0x4e0 net/ipv6/ip6_output.c:219
NF_HOOK_COND include/linux/netfilter.h:307 [inline]
ip6_output+0x342/0x580 net/ipv6/ip6_output.c:246
ip6_send_skb+0x1d7/0x3c0 net/ipv6/ip6_output.c:1984
udp_v6_send_skb+0x9a5/0x1770 net/ipv6/udp.c:1442
udp_v6_push_pending_frames+0xa2/0x140 net/ipv6/udp.c:1469
udpv6_sendmsg+0xfe0/0x2830 net/ipv6/udp.c:1759
sock_sendmsg_nosec net/socket.c:727 [inline]
__sock_sendmsg+0xe5/0x270 net/socket.c:742
__sys_sendto+0x3eb/0x580 net/socket.c:2206
__do_sys_sendto net/socket.c:2213 [inline]
__se_sys_sendto net/socket.c:2209 [inline]
__x64_sys_sendto+0xde/0x100 net/socket.c:2209
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xd2/0xf20 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x7f67b4d9c629
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f67b5c98028 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00007f67b5015fa0 RCX: 00007f67b4d9c629
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 00007f67b4e32b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000040000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f67b5016038 R14: 00007f67b5015fa0 R15: 00007ffe3cb66dd8
</TASK>

Published: 2026-05-06

Score: 7.5 High

EPSS: < 1% Very Low

KEV: No

Impact:

Action:

Analysis

Impact

A null‑pointer dereference is triggered when the UDP Lite socket initialization fails, leaving udp_sk->udp_prod_queue unset. The subsequent __udp_enqueue_schedule_skb call dereferences this null pointer, causing KASAN to report a fault and the kernel to panic. Based on the KASAN log excerpt, the fault would result in a kernel crash that requires a reboot, thereby providing a local denial‑of‑service effect.

Affected Systems

The vulnerability exists in the Linux kernel’s udplite subsystem across both IPv4 and IPv6. All kernel releases that have not incorporated the fixing commit are affected, covering all distributions, cloud images, and embedded devices shipping the unpatched upstream source. No specific version range is provided by the CNA, so the risk applies to any kernel prior to the patch.

Risk and Exploitability

The CVSS score of 7.5 indicates high severity. The EPSS score of 0.00017 (<1%) and the vulnerability is not listed in the CISA KEV catalog, implying no confirmed public exploitation. The likely attack vector is sending specially crafted UDP Lite traffic that forces the enqueue routine to execute while the socket is in a failed state. Based on the description, it is inferred that the resulting kernel crash would lead to service disruption in affected environments.

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions

Linux

unaffected

Version	Status	Constraints
`b650bf0977d34c52befb31a9fa711534e11b220f`	affected	< f27030ac5bef47d997cfac05a3d188aa69f4df7f
`b650bf0977d34c52befb31a9fa711534e11b220f`	affected	< 0f13fa087ead642ea1eb5fdb6eb092c913ef06b7
`b650bf0977d34c52befb31a9fa711534e11b220f`	affected	< 470c7ca2b4c3e3a51feeb952b7f97a775b5c49cd

Linux

affected

Version	Status	Constraints
`6.18`	affected	—
`0`	unaffected	< 6.18
`6.18.16`	unaffected	≤ 6.18.*
`6.19.6`	unaffected	≤ 6.19.*
`7.0`	unaffected	≤ *

Configuration 1 [-]

OR	cpe:2.3:o:linux:linux_kernel::::::::
	cpe:2.3:o:linux:linux_kernel::::::::
	cpe:2.3:o:linux:linux_kernel:7.0:rc1::::::

No data.

Vendor Product Confidence Versions

Linux

Linux Kernel

99%

Version	Status	Scheme	Platform
`[b650bf0977d34c52befb31a9fa711534e11b220f,f27030ac5bef47d997cfac05a3d188aa69f4df7f)`	affected	code_commit	—
`[b650bf0977d34c52befb31a9fa711534e11b220f,0f13fa087ead642ea1eb5fdb6eb092c913ef06b7)`	affected	code_commit	—
`[b650bf0977d34c52befb31a9fa711534e11b220f,470c7ca2b4c3e3a51feeb952b7f97a775b5c49cd)`	affected	code_commit	—

Linux

Linux Kernel

99%

Version	Status	Scheme	Platform
`6.18`	affected	generic	—
`[0,6.18)`	unaffected	generic	—
`[6.18.16,6.19.0)`	unaffected	generic	—
`[6.19.6,6.20.0)`	unaffected	generic	—
`[7.0,*]`	unaffected	generic	—

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Remediation

No vendor fix or workaround currently provided.

OpenCVE Recommended Actions

Apply the latest Linux kernel patch that includes the CVE-2026-43164 fix.
Disable UDP Lite on the affected hosts by dropping UDP Lite packets with firewall rules.
Monitor kernel logs for KASAN messages indicating null‑pointer dereference and apply the patch if such a log entry appears.

Generated by OpenCVE AI on May 8, 2026 at 17:36 UTC.

Tracking

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Advisories

No advisories yet.

No CVSS v4.0

Attack Vector Network

Attack Complexity Low

Privileges Required None

Scope Unchanged

Confidentiality Impact None

Integrity Impact None

Availability Impact High

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

The EPSS score is 0.00058.

Key SSVC decision points have not yet been added.

References

Link	Providers
https://git.kernel.org/stable/c/0f13fa087ead642ea1eb5fdb6eb092c913ef06b7
https://git.kernel.org/stable/c/470c7ca2b4c3e3a51feeb952b7f97a775b5c49cd
https://git.kernel.org/stable/c/f27030ac5bef47d997cfac05a3d188aa69f4df7f
https://lore.kernel.org/linux-cve-announce/2026050633-CVE-2026-43164-c1bc@gregkh/T
https://nvd.nist.gov/vuln/detail/CVE-2026-43164
https://www.cve.org/CVERecord?id=CVE-2026-43164

History

Wed, 13 May 2026 21:30:00 +0000

Type	Values Removed	Values Added
CPEs		cpe:2.3:o:linux:linux_kernel:7.0:rc1::::::

Fri, 08 May 2026 13:00:00 +0000

Type	Values Removed	Values Added
Metrics	cvssV3_1 `{'score': 5.5, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'}`	cvssV3_1 `{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}`

Thu, 07 May 2026 00:15:00 +0000

Type	Values Removed	Values Added
References		https://lore.kernel.org/linux-cve-announce/2026050633-CVE-2026-43164-c1bc@gregkh/T https://nvd.nist.gov/vuln/detail/CVE-2026-43164 https://www.cve.org/CVERecord?id=CVE-2026-43164
Metrics	threat_severity `None`	cvssV3_1 `{'score': 5.5, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'}` threat_severity `Moderate`

Wed, 06 May 2026 14:45:00 +0000

Type	Values Removed	Values Added
Weaknesses		CWE-476

Wed, 06 May 2026 12:15:00 +0000

Type	Values Removed	Values Added
Description		In the Linux kernel, the following vulnerability has been resolved: udplite: Fix null-ptr-deref in __udp_enqueue_schedule_skb(). syzbot reported null-ptr-deref of udp_sk(sk)->udp_prod_queue. [0] Since the cited commit, udp_lib_init_sock() can fail, as can udp_init_sock() and udpv6_init_sock(). Let's handle the error in udplite_sk_init() and udplitev6_sk_init(). [0]: BUG: KASAN: null-ptr-deref in instrument_atomic_read include/linux/instrumented.h:82 [inline] BUG: KASAN: null-ptr-deref in atomic_read include/linux/atomic/atomic-instrumented.h:32 [inline] BUG: KASAN: null-ptr-deref in __udp_enqueue_schedule_skb+0x151/0x1480 net/ipv4/udp.c:1719 Read of size 4 at addr 0000000000000008 by task syz.2.18/2944 CPU: 1 UID: 0 PID: 2944 Comm: syz.2.18 Not tainted syzkaller #0 PREEMPTLAZY Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 Call Trace: <IRQ> dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 kasan_report+0xa2/0xe0 mm/kasan/report.c:595 check_region_inline mm/kasan/generic.c:-1 [inline] kasan_check_range+0x264/0x2c0 mm/kasan/generic.c:200 instrument_atomic_read include/linux/instrumented.h:82 [inline] atomic_read include/linux/atomic/atomic-instrumented.h:32 [inline] __udp_enqueue_schedule_skb+0x151/0x1480 net/ipv4/udp.c:1719 __udpv6_queue_rcv_skb net/ipv6/udp.c:795 [inline] udpv6_queue_rcv_one_skb+0xa2e/0x1ad0 net/ipv6/udp.c:906 udp6_unicast_rcv_skb+0x227/0x380 net/ipv6/udp.c:1064 ip6_protocol_deliver_rcu+0xe17/0x1540 net/ipv6/ip6_input.c:438 ip6_input_finish+0x191/0x350 net/ipv6/ip6_input.c:489 NF_HOOK+0x354/0x3f0 include/linux/netfilter.h:318 ip6_input+0x16c/0x2b0 net/ipv6/ip6_input.c:500 NF_HOOK+0x354/0x3f0 include/linux/netfilter.h:318 __netif_receive_skb_one_core net/core/dev.c:6149 [inline] __netif_receive_skb+0xd3/0x370 net/core/dev.c:6262 process_backlog+0x4d6/0x1160 net/core/dev.c:6614 __napi_poll+0xae/0x320 net/core/dev.c:7678 napi_poll net/core/dev.c:7741 [inline] net_rx_action+0x60d/0xdc0 net/core/dev.c:7893 handle_softirqs+0x209/0x8d0 kernel/softirq.c:622 do_softirq+0x52/0x90 kernel/softirq.c:523 </IRQ> <TASK> __local_bh_enable_ip+0xe7/0x120 kernel/softirq.c:450 local_bh_enable include/linux/bottom_half.h:33 [inline] rcu_read_unlock_bh include/linux/rcupdate.h:924 [inline] __dev_queue_xmit+0x109c/0x2dc0 net/core/dev.c:4856 __ip6_finish_output net/ipv6/ip6_output.c:-1 [inline] ip6_finish_output+0x158/0x4e0 net/ipv6/ip6_output.c:219 NF_HOOK_COND include/linux/netfilter.h:307 [inline] ip6_output+0x342/0x580 net/ipv6/ip6_output.c:246 ip6_send_skb+0x1d7/0x3c0 net/ipv6/ip6_output.c:1984 udp_v6_send_skb+0x9a5/0x1770 net/ipv6/udp.c:1442 udp_v6_push_pending_frames+0xa2/0x140 net/ipv6/udp.c:1469 udpv6_sendmsg+0xfe0/0x2830 net/ipv6/udp.c:1759 sock_sendmsg_nosec net/socket.c:727 [inline] __sock_sendmsg+0xe5/0x270 net/socket.c:742 __sys_sendto+0x3eb/0x580 net/socket.c:2206 __do_sys_sendto net/socket.c:2213 [inline] __se_sys_sendto net/socket.c:2209 [inline] __x64_sys_sendto+0xde/0x100 net/socket.c:2209 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xd2/0xf20 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x76/0x7e RIP: 0033:0x7f67b4d9c629 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f67b5c98028 EFLAGS: 00000246 ORIG_RAX: 000000000000002c RAX: ffffffffffffffda RBX: 00007f67b5015fa0 RCX: 00007f67b4d9c629 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003 RBP: 00007f67b4e32b39 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000040000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f67b5016038 R14: 00007f67b5015fa0 R15: 00007ffe3cb66dd8 </TASK>
Title		udplite: Fix null-ptr-deref in __udp_enqueue_schedule_skb().
First Time appeared		Linux Linux linux Kernel
CPEs		cpe:2.3:o:linux:linux_kernel::::::::
Vendors & Products		Linux Linux linux Kernel
References		https://git.kernel.org/stable/c/0f13fa087ead642ea1eb5fdb6eb092c913ef06b7 https://git.kernel.org/stable/c/470c7ca2b4c3e3a51feeb952b7f97a775b5c49cd https://git.kernel.org/stable/c/f27030ac5bef47d997cfac05a3d188aa69f4df7f

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Linux Linux Kernel

MITRE

Status: PUBLISHED

Assigner: Linux

Published: 2026-05-06T11:27:41.928Z

Updated: 2026-05-11T22:19:00.252Z

Reserved: 2026-05-01T14:12:55.990Z

Link: CVE-2026-43164

Vulnrichment

No data.

NVD

Status : Analyzed

Published: 2026-05-06T12:16:34.540

Modified: 2026-05-13T21:19:27.667

Link: CVE-2026-43164

Redhat

Severity : Moderate

Publid Date: 2026-05-06T00:00:00Z

Links: CVE-2026-43164 - Bugzilla

OpenCVE Enrichment

Updated: 2026-05-08T17:45:13Z

Weaknesses

CWE-476

Impact

Affected Systems

Risk and Exploitability

Tracking

Attack Vector Network

Attack Complexity Low

Privileges Required None

Scope Unchanged

Confidentiality Impact None

Integrity Impact None

Availability Impact High

User Interaction None

Subscriptions

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