In the Linux kernel, the following vulnerability has been resolved: llc: reserve device headroom for allocated frames llc_alloc_frame() reserves… (CVE-2026-98526)

The Linux kernel vulnerability (CVE-2026-98526) relates to the llc_alloc_frame() function in the LLC layer, which previously reserved link-layer headroom based solely on device type. This approach failed for stacked Ethernet devices such as VLAN devices, where vlan_dev_hard_header() adds a VLAN header before the lower device's Ethernet header. Consequently, an LLC response on these devices could cause skb headroom underflow in eth_header(). The vulnerability was addressed by modifying the reservation logic to use LL_RESERVED_SPACE(), ensuring the device's actual required headroom is accounted for while preserving existing device-type checks.

The vulnerability could lead to skb headroom underflow in the kernel's network stack when handling LLC responses on VLAN or other stacked Ethernet devices. This may cause memory corruption or instability in the network subsystem. No known exploits in the wild have been reported.

A fix has been implemented in the Linux kernel to address this issue by correctly reserving device headroom using LL_RESERVED_SPACE(). Users should update to the patched Linux kernel version containing this fix. Since this is a kernel-level vulnerability, applying the official kernel update is the recommended remediation.