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

net: macb: fix NULL pointer dereference on unbind with fixed-link

When the device tree describes a fixed-link and has no "mdio" child
node, macb_mii_init() returns early without allocating the MDIO bus,
leaving bp->mii_bus as NULL.

Two cleanup paths then dereference this NULL bus:

1. On driver unbind, macb_remove() unconditionally calls
mdiobus_unregister(bp->mii_bus), which oopses:

Unable to handle kernel NULL pointer dereference at virtual address 00000000000004a8
pc : mdiobus_unregister+0x14/0xa4
lr : macb_remove+0x38/0xa4
Call trace:
mdiobus_unregister+0x14/0xa4 (P)
macb_remove+0x38/0xa4
platform_remove+0x20/0x30
device_release_driver_internal+0x1c8/0x224
unbind_store+0xb4/0xbc

2. On the probe error path in macb_probe(), reached when
macb_mii_init() has succeeded but a subsequent step fails, the
err_out_unregister_mdio label runs the same unconditional cleanup.

mdiobus_unregister() and mdiobus_free() do not guard against a NULL
bus, so guard the calls in both macb_remove() and the probe error
path.

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Advisories
Source ID Title
Debian DLA Debian DLA DLA-4817-1 linux-6.12 security update
Debian DLA Debian DLA DLA-4841-1 linux security update
Debian DSA Debian DSA DSA-6528-1 linux security update
Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

History

Sat, 03 Oct 2026 11:15:00 +0000


Tue, 29 Sep 2026 13:15:00 +0000

Type Values Removed Values Added
References
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


Fri, 25 Sep 2026 17:00:00 +0000

Type Values Removed Values Added
Weaknesses CWE-476

Fri, 25 Sep 2026 10:30:00 +0000

Type Values Removed Values Added
Description In the Linux kernel, the following vulnerability has been resolved: net: macb: fix NULL pointer dereference on unbind with fixed-link When the device tree describes a fixed-link and has no "mdio" child node, macb_mii_init() returns early without allocating the MDIO bus, leaving bp->mii_bus as NULL. Two cleanup paths then dereference this NULL bus: 1. On driver unbind, macb_remove() unconditionally calls mdiobus_unregister(bp->mii_bus), which oopses: Unable to handle kernel NULL pointer dereference at virtual address 00000000000004a8 pc : mdiobus_unregister+0x14/0xa4 lr : macb_remove+0x38/0xa4 Call trace: mdiobus_unregister+0x14/0xa4 (P) macb_remove+0x38/0xa4 platform_remove+0x20/0x30 device_release_driver_internal+0x1c8/0x224 unbind_store+0xb4/0xbc 2. On the probe error path in macb_probe(), reached when macb_mii_init() has succeeded but a subsequent step fails, the err_out_unregister_mdio label runs the same unconditional cleanup. mdiobus_unregister() and mdiobus_free() do not guard against a NULL bus, so guard the calls in both macb_remove() and the probe error path.
Title net: macb: fix NULL pointer dereference on unbind with fixed-link
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
References

Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2026-10-19T09:12:13.751Z

Reserved: 2026-09-25T10:19:56.068Z

Link: CVE-2026-98008

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-09-25T11:17:29.080

Modified: 2026-10-19T10:17:52.177

Link: CVE-2026-98008

cve-icon Redhat

Severity : Moderate

Publid Date: 2026-09-25T00:00:00Z

Links: CVE-2026-98008 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-09-30T14:30:18Z

Weaknesses