CVE-2026-43456 - Vulnerability Details

- bonding: fix type confusion in bond_setup_by_slave()

Description

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

bonding: fix type confusion in bond_setup_by_slave()

kernel BUG at net/core/skbuff.c:2306!
Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI
RIP: 0010:pskb_expand_head+0xa08/0xfe0 net/core/skbuff.c:2306
RSP: 0018:ffffc90004aff760 EFLAGS: 00010293
RAX: 0000000000000000 RBX: ffff88807e3c8780 RCX: ffffffff89593e0e
RDX: ffff88807b7c4900 RSI: ffffffff89594747 RDI: ffff88807b7c4900
RBP: 0000000000000820 R08: 0000000000000005 R09: 0000000000000000
R10: 00000000961a63e0 R11: 0000000000000000 R12: ffff88807e3c8780
R13: 00000000961a6560 R14: dffffc0000000000 R15: 00000000961a63e0
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fe1a0ed8df0 CR3: 000000002d816000 CR4: 00000000003526f0
Call Trace:
<TASK>
ipgre_header+0xdd/0x540 net/ipv4/ip_gre.c:900
dev_hard_header include/linux/netdevice.h:3439 [inline]
packet_snd net/packet/af_packet.c:3028 [inline]
packet_sendmsg+0x3ae5/0x53c0 net/packet/af_packet.c:3108
sock_sendmsg_nosec net/socket.c:727 [inline]
__sock_sendmsg net/socket.c:742 [inline]
____sys_sendmsg+0xa54/0xc30 net/socket.c:2592
___sys_sendmsg+0x190/0x1e0 net/socket.c:2646
__sys_sendmsg+0x170/0x220 net/socket.c:2678
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x106/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe1a0e6c1a9

When a non-Ethernet device (e.g. GRE tunnel) is enslaved to a bond,
bond_setup_by_slave() directly copies the slave's header_ops to the
bond device:

bond_dev->header_ops = slave_dev->header_ops;

This causes a type confusion when dev_hard_header() is later called
on the bond device. Functions like ipgre_header(), ip6gre_header(),all use
netdev_priv(dev) to access their device-specific private data. When
called with the bond device, netdev_priv() returns the bond's private
data (struct bonding) instead of the expected type (e.g. struct
ip_tunnel), leading to garbage values being read and kernel crashes.

Fix this by introducing bond_header_ops with wrapper functions that
delegate to the active slave's header_ops using the slave's own
device. This ensures netdev_priv() in the slave's header functions
always receives the correct device.

The fix is placed in the bonding driver rather than individual device
drivers, as the root cause is bond blindly inheriting header_ops from
the slave without considering that these callbacks expect a specific
netdev_priv() layout.

The type confusion can be observed by adding a printk in
ipgre_header() and running the following commands:

ip link add dummy0 type dummy
ip addr add 10.0.0.1/24 dev dummy0
ip link set dummy0 up
ip link add gre1 type gre local 10.0.0.1
ip link add bond1 type bond mode active-backup
ip link set gre1 master bond1
ip link set gre1 up
ip link set bond1 up
ip addr add fe80::1/64 dev bond1

Published: 2026-05-08

Score: 7.8 High

EPSS: < 1% Very Low

KEV: No

Impact:

Action:

Analysis

Impact

The vulnerability arises when the Linux bonding driver copies a non-Ethernet slave’s header_ops directly into the bonded interface. Functions such as ipgre_header() then call netdev_priv() assuming the private data belongs to the slave’s driver, but the bond’s private data is of a different type. This type confusion causes garbage reads and a kernel BUG that leads to a crash, resulting in a kernel panic and a system-wide denial of service.

Affected Systems

All Linux kernels that include the vulnerable bonding driver and lack the fix are impacted. Linux distributions that ship the core kernel before the patch commit are affected. The specific version range is any kernel older than commit 6ac890f1d60ac3707ee8dae15a67d9a833e49956, as the patch replaces the buggy copy of header_ops.

Risk and Exploitability

The CVSS score of 7.8 indicates a medium to high severity for this kernel panic. The EPSS score of < 1% suggests a very low exploitation probability. The vulnerability is not listed in the CISA KEV catalog, indicating no publicly known exploits. Based on the description, it is inferred that the likely attack vector requires privileged access to configure bonding interfaces; an attacker that can add a non-Ethernet slave such as a GRE tunnel to a bond can trigger the crash during traffic handling.

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
`1284cd3a2b740d0118458d2ea470a1e5bc19b187`	affected	< 9baf26a91565b7bb2b1d9f99aaf884a2b28c2f6d
`1284cd3a2b740d0118458d2ea470a1e5bc19b187`	affected	< 6ac890f1d60ac3707ee8dae15a67d9a833e49956
`1284cd3a2b740d0118458d2ea470a1e5bc19b187`	affected	< 95597d11dc8bddb2b9a051c9232000bfbb5e43ba
`1284cd3a2b740d0118458d2ea470a1e5bc19b187`	affected	< 950803f7254721c1c15858fbbfae3deaaeeecb11

Linux

affected

Version	Status	Constraints
`2.6.24`	affected	—
`0`	unaffected	< 2.6.24
`6.12.78`	unaffected	≤ 6.12.*
`6.18.19`	unaffected	≤ 6.18.*
`6.19.9`	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::::::::
	cpe:2.3:o:linux:linux_kernel:7.0:rc1::::::
	cpe:2.3:o:linux:linux_kernel:7.0:rc2::::::
	cpe:2.3:o:linux:linux_kernel:7.0:rc3::::::

No data.

Vendor Product Confidence Versions

Linux

Linux Kernel

99%

Version	Status	Scheme	Platform
`[1284cd3a2b740d0118458d2ea470a1e5bc19b187,9baf26a91565b7bb2b1d9f99aaf884a2b28c2f6d)`	affected	code_commit	—
`[1284cd3a2b740d0118458d2ea470a1e5bc19b187,6ac890f1d60ac3707ee8dae15a67d9a833e49956)`	affected	code_commit	—
`[1284cd3a2b740d0118458d2ea470a1e5bc19b187,95597d11dc8bddb2b9a051c9232000bfbb5e43ba)`	affected	code_commit	—
`[1284cd3a2b740d0118458d2ea470a1e5bc19b187,950803f7254721c1c15858fbbfae3deaaeeecb11)`	affected	code_commit	—

Linux

Linux Kernel

99%

Version	Status	Scheme	Platform
`2.6.24`	affected	semver	—
`[0,2.6.24)`	unaffected	semver	—
`[6.12.78,6.13.0)`	unaffected	semver	—
`[6.18.19,6.19.0)`	unaffected	semver	—
`[6.19.9,6.20.0)`	unaffected	semver	—
`[7.0,*]`	unaffected	generic	—

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Remediation

No vendor fix or workaround currently provided.

OpenCVE Recommended Actions

Update the system kernel to a version that includes the bonding driver fix (commit 6ac890f1d60ac3707ee8dae15a67d9a833e49956).
Until the patch is applied, avoid attaching GRE or other non-Ethernet slaves to bonding interfaces; bring affected bonds and slaves down and reconfigure after the patch.
If the vendor has not released a patched kernel, manually apply the commit to the bonding driver source, rebuild the kernel, and reboot.

Generated by OpenCVE AI on May 20, 2026 at 19:25 UTC.

Tracking

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Advisories

No advisories yet.

No CVSS v4.0

Attack Vector Local

Attack Complexity Low

Privileges Required Low

Scope Unchanged

Confidentiality Impact High

Integrity Impact High

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 0.00013.

Key SSVC decision points have not yet been added.

References

Link	Providers
https://git.kernel.org/stable/c/6ac890f1d60ac3707ee8dae15a67d9a833e49956
https://git.kernel.org/stable/c/950803f7254721c1c15858fbbfae3deaaeeecb11
https://git.kernel.org/stable/c/95597d11dc8bddb2b9a051c9232000bfbb5e43ba
https://git.kernel.org/stable/c/9baf26a91565b7bb2b1d9f99aaf884a2b28c2f6d
https://lore.kernel.org/linux-cve-announce/2026050859-CVE-2026-43456-ae60@gregkh/T
https://nvd.nist.gov/vuln/detail/CVE-2026-43456
https://www.cve.org/CVERecord?id=CVE-2026-43456

History

Wed, 20 May 2026 18:15:00 +0000

Type	Values Removed	Values Added
Weaknesses		CWE-908
CPEs		cpe:2.3:o:linux:linux_kernel:7.0:rc1:::::: cpe:2.3:o:linux:linux_kernel:7.0:rc2:::::: cpe:2.3:o:linux:linux_kernel:7.0:rc3::::::

Mon, 11 May 2026 07:45:00 +0000

Type	Values Removed	Values Added
Metrics	cvssV3_1 `{'score': 7.0, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H'}`	cvssV3_1 `{'score': 7.8, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'}`

Sat, 09 May 2026 12:15:00 +0000

Type	Values Removed	Values Added
Weaknesses		CWE-843
References		https://lore.kernel.org/linux-cve-announce/2026050859-CVE-2026-43456-ae60@gregkh/T https://nvd.nist.gov/vuln/detail/CVE-2026-43456 https://www.cve.org/CVERecord?id=CVE-2026-43456
Metrics	threat_severity `None`	cvssV3_1 `{'score': 7.0, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H'}` threat_severity `Moderate`

Fri, 08 May 2026 14:45:00 +0000

Type	Values Removed	Values Added
Description		In the Linux kernel, the following vulnerability has been resolved: bonding: fix type confusion in bond_setup_by_slave() kernel BUG at net/core/skbuff.c:2306! Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI RIP: 0010:pskb_expand_head+0xa08/0xfe0 net/core/skbuff.c:2306 RSP: 0018:ffffc90004aff760 EFLAGS: 00010293 RAX: 0000000000000000 RBX: ffff88807e3c8780 RCX: ffffffff89593e0e RDX: ffff88807b7c4900 RSI: ffffffff89594747 RDI: ffff88807b7c4900 RBP: 0000000000000820 R08: 0000000000000005 R09: 0000000000000000 R10: 00000000961a63e0 R11: 0000000000000000 R12: ffff88807e3c8780 R13: 00000000961a6560 R14: dffffc0000000000 R15: 00000000961a63e0 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fe1a0ed8df0 CR3: 000000002d816000 CR4: 00000000003526f0 Call Trace: <TASK> ipgre_header+0xdd/0x540 net/ipv4/ip_gre.c:900 dev_hard_header include/linux/netdevice.h:3439 [inline] packet_snd net/packet/af_packet.c:3028 [inline] packet_sendmsg+0x3ae5/0x53c0 net/packet/af_packet.c:3108 sock_sendmsg_nosec net/socket.c:727 [inline] __sock_sendmsg net/socket.c:742 [inline] ____sys_sendmsg+0xa54/0xc30 net/socket.c:2592 ___sys_sendmsg+0x190/0x1e0 net/socket.c:2646 __sys_sendmsg+0x170/0x220 net/socket.c:2678 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x106/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fe1a0e6c1a9 When a non-Ethernet device (e.g. GRE tunnel) is enslaved to a bond, bond_setup_by_slave() directly copies the slave's header_ops to the bond device: bond_dev->header_ops = slave_dev->header_ops; This causes a type confusion when dev_hard_header() is later called on the bond device. Functions like ipgre_header(), ip6gre_header(),all use netdev_priv(dev) to access their device-specific private data. When called with the bond device, netdev_priv() returns the bond's private data (struct bonding) instead of the expected type (e.g. struct ip_tunnel), leading to garbage values being read and kernel crashes. Fix this by introducing bond_header_ops with wrapper functions that delegate to the active slave's header_ops using the slave's own device. This ensures netdev_priv() in the slave's header functions always receives the correct device. The fix is placed in the bonding driver rather than individual device drivers, as the root cause is bond blindly inheriting header_ops from the slave without considering that these callbacks expect a specific netdev_priv() layout. The type confusion can be observed by adding a printk in ipgre_header() and running the following commands: ip link add dummy0 type dummy ip addr add 10.0.0.1/24 dev dummy0 ip link set dummy0 up ip link add gre1 type gre local 10.0.0.1 ip link add bond1 type bond mode active-backup ip link set gre1 master bond1 ip link set gre1 up ip link set bond1 up ip addr add fe80::1/64 dev bond1
Title		bonding: fix type confusion in bond_setup_by_slave()
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/6ac890f1d60ac3707ee8dae15a67d9a833e49956 https://git.kernel.org/stable/c/950803f7254721c1c15858fbbfae3deaaeeecb11 https://git.kernel.org/stable/c/95597d11dc8bddb2b9a051c9232000bfbb5e43ba https://git.kernel.org/stable/c/9baf26a91565b7bb2b1d9f99aaf884a2b28c2f6d

Subscriptions

Linux Linux Kernel

MITRE

Status: PUBLISHED

Assigner: Linux

Published: 2026-05-08T14:22:20.036Z

Updated: 2026-05-11T22:24:56.355Z

Reserved: 2026-05-01T14:12:56.010Z

Link: CVE-2026-43456

Vulnrichment

No data.

NVD

Status : Analyzed

Published: 2026-05-08T15:16:58.387

Modified: 2026-05-20T18:03:53.577

Link: CVE-2026-43456

Redhat

Severity : Moderate

Publid Date: 2026-05-08T00:00:00Z

Links: CVE-2026-43456 - Bugzilla

OpenCVE Enrichment

Updated: 2026-05-20T19:30:37Z

Weaknesses

Impact

Affected Systems

Risk and Exploitability

Tracking

Attack Vector Local

Attack Complexity Low

Privileges Required Low

Scope Unchanged

Confidentiality Impact High

Integrity Impact High

Availability Impact High

User Interaction None

Subscriptions

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