CVE-2026-98008 net: macb: fix NULL pointer dereference on unbind with fixed-link
A local attacker with high privileges can cause a kernel crash by unbinding a network driver configured with a fixed-link and no MDIO node.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-98008?
CVE-2026-98008 is a vulnerability in Linux, published on 25 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official 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.
Which versions are affected by CVE-2026-98008?
How do I fix CVE-2026-98008?
Apply the vendor's patch.
Is CVE-2026-98008 being exploited?
There is no known exploitation of CVE-2026-98008 in the wild and no public exploit code.
Sources
Also known as AZL-104673, BELL-CVE-2026-98008, DEBIAN-CVE-2026-98008, GHSA-h4xg-972w-f7c3, UBUNTU-CVE-2026-98008.