CVE-2026-53248: Linux Kernel airoha Use-After-Free Vulnerability (CVSS 8.8)

Technical summary

CVE-2026-53248 is a use-after-free (CWE-416) in the airoha metadata destination handling path. The vulnerable function airoha_metadata_dst_free() calls metadata_dst_free() which invokes kfree() directly, bypassing RCU grace period enforcement. In the RX path, skb_dst_set_noref() establishes non-refcounted pointers to metadata_dst objects that must remain valid under RCU read-side critical sections. When the driver tears down the destination without respecting RCU semantics, a race condition allows skb packet buffers holding stale pointers to dereference freed memory. The remediation replaces the direct kfree() path with dst_release(), which properly transitions through refcount decrement and uses call_rcu_hurry() to schedule deallocation only after RCU readers complete.

Business impact

This vulnerability can lead to kernel memory corruption and denial of service on systems running affected airoha-based network hardware. Exploitation requires network-level triggering via malformed packets, making it reachable from both local and remote attack vectors depending on network configuration. A successful exploit can crash the kernel or corrupt system memory, resulting in unplanned downtime and potential data loss. Organizations relying on airoha hardware for network infrastructure should prioritize patching to prevent service interruption.

Affected systems

The Linux kernel is affected, specifically systems with airoha network driver support enabled. This includes embedded devices, routers, and network appliances built on MediaTek/airoha chipsets that run a vulnerable Linux kernel version. The vulnerability is present in mainline and stable kernel releases; verify your specific kernel version against the Linux kernel advisory for exact affected series and patch availability.

Exploitability

Exploitation is network-adjacent; an attacker must send crafted network packets to trigger the race condition between packet reception and driver teardown. The CVSS vector (AV:N/AC:L/PR:N/UI:R) indicates network access with low attack complexity and user interaction requirement. While the user interaction component may seem limiting, it likely reflects the need for the driver to be actively processing traffic during teardown. Given the low barrier to packet manipulation and the severity of memory corruption outcomes, this is a practical exploit scenario for attackers with network access to affected systems.

Remediation

Apply a Linux kernel update that includes the fix replacing airoha_metadata_dst_free() call sequences with proper dst_release() semantics. Verify the patch against the official Linux kernel Git repository commit that resolves this issue. For distribution-specific kernels (Ubuntu, Red Hat, Debian, etc.), check your vendor's security advisory for backported patches. Until patched, limit network exposure of affected devices and monitor system logs for kernel oops or memory corruption warnings that may indicate exploitation attempts.

Patch guidance

Obtain and install a patched Linux kernel from your distribution or device vendor that includes the RCU fix for airoha metadata destination handling. The fix modifies the airoha driver's teardown path to use dst_release() instead of direct metadata_dst_free() calls. Verify patch application by confirming the kernel version reports as patched post-reboot. For embedded devices, check with the OEM for firmware updates; do not assume automatic kernel updates. Test in a non-production environment first if feasible, as kernel updates may affect driver behavior or require hardware reconfiguration.

Detection guidance

Monitor system logs for kernel panic messages, particularly those involving 'use-after-free', 'RCU', or 'airoha' driver references. Kernel Address Sanitizer (KASAN) or similar runtime checkers will flag the memory corruption if enabled at build time. Network intrusion detection signatures targeting malformed airoha-protocol packets may assist, though this is driver-specific and unlikely to be widely available. Focus on identifying affected kernel versions in your infrastructure via package management tools (rpm -q, dpkg -l) and cross-referencing against patched version numbers from your vendor advisory.

Why prioritize this

This HIGH severity vulnerability combines network-reachable attack surface, kernel-level memory safety impact, and straightforward exploitation mechanics. The CVSS 8.8 score reflects the combination of high confidentiality, integrity, and availability impact. Although KEV status is not currently active, the simplicity of triggering packet-driven races and the critical role of network drivers in system stability make this a near-term patching priority, particularly for network-facing devices or those in high-traffic environments.

Risk score, explained

CVSS 3.1 score of 8.8 (HIGH) is assigned based on: Network attack vector (AV:N) allowing remote exploitation, low attack complexity (AC:L) requiring no special privilege or account, no privilege requirement (PR:N), user interaction requirement (UI:R) for race condition timing, unchanged scope (S:U), and high impact across confidentiality, integrity, and availability (C:H/I:H/A:H). The user interaction element reflects the dependency on active packet processing during driver teardown rather than requiring explicit user action; the practical exploitability remains high in typical network scenarios.

Frequently asked questions