CVE-2026-53318: Linux Kernel MT7925 WiFi Driver NULL Pointer Dereference Vulnerability

Technical summary

CVE-2026-53318 is a NULL pointer dereference vulnerability in the mt76 WiFi driver module, specifically in the mt7925_tx_check_aggr() function. The flaw occurs because the driver dereferences the 'sta' (station) pointer before validating that it is not NULL. Under certain conditions—such as unexpected wireless frame transmission scenarios or race conditions during station management—the pointer may be NULL, causing a kernel panic. The fix involves reordering the NULL check to occur before any pointer dereference operations. This is classified as CWE-476 (NULL Pointer Dereference).

Business impact

While the immediate impact is limited to denial of service on affected systems, the business implications depend on deployment context. Systems running headless servers or embedded devices with MT7925 WiFi may experience unexpected reboots or service interruptions. Organizations relying on WiFi-connected Linux systems for critical functions—such as IoT gateways, edge computing nodes, or mobile workstations—could face availability impact. The local privilege requirement means external attackers cannot exploit this remotely, but malicious insiders or compromised local accounts present a realistic threat in multi-tenant or shared environments.

Affected systems

This vulnerability affects the Linux kernel across all versions shipping the vulnerable mt76 WiFi driver code for MT7925 chipsets. Any Linux system using MediaTek MT7925 WiFi hardware (found in some laptops, embedded devices, and wireless modules) is at risk. The vulnerability was resolved in a kernel update; specific patched versions should be verified against the Linux kernel's official security advisories and your distribution's patch timeline. Systems using alternative WiFi chipsets or drivers are not affected.

Exploitability

Exploitation requires local access to the affected system (AV:L) and standard user privileges (PR:L), making this a limited-scope threat. No user interaction is needed once access is obtained (UI:N). An attacker with a local account could trigger the crash through crafted wireless transmission patterns or by interacting with the mt7925 driver in unexpected ways. The vulnerability is not known to be actively exploited in the wild, nor is it tracked on the CISA Known Exploited Vulnerabilities (KEV) catalog. However, the straightforward nature of the bug (missing NULL check) means proof-of-concept development would be relatively straightforward for a knowledgeable attacker.

Remediation

Update the Linux kernel to a patched version released after June 26, 2026. Check your distribution's security advisory pages for the specific kernel version addressing this issue. Most major distributions (Ubuntu, Red Hat, Debian, SUSE) have or will release kernel updates; timing varies by release cycle and support tier. For systems where immediate kernel updates are not feasible, restrict local access and monitor for signs of system crashes correlated with wireless driver activity.

Patch guidance

Apply the latest Linux kernel update available from your distribution. After updating, verify the new kernel version is active by rebooting the system. Test WiFi connectivity to confirm the driver is functioning correctly post-patch. For enterprise deployments, validate the patch in a test environment before rolling out broadly. Verify against your vendor's security advisory that the specific update addresses CVE-2026-53318. If your distribution has not yet released a patch, monitor the Linux kernel security mailing list and your vendor's advisory pages for availability.

Detection guidance

Monitor system logs for kernel panic messages or crashes mentioning 'mt7925', 'mt76', or NULL pointer dereferences in the wireless subsystem. Look for repeated reboot events without clear user action, particularly on systems with MT7925 adapters. Kernel crash dumps (dmesg logs) will show the dereference location in mt7925_tx_check_aggr(). Organizations with centralized logging can correlate WiFi driver errors with system downtime. Host-based monitoring for unexpected kernel panics on MT7925-equipped systems can serve as an early warning of exploitation attempts.

Why prioritize this

While the CVSS score of 5.5 (MEDIUM) reflects the local-access-only requirement, this vulnerability should not be deprioritized solely on that metric. The kernel-level nature of the flaw and its potential to cause unplanned system outages warrant prompt patching for any organization running MT7925 devices. If your environment does not include MT7925 WiFi hardware, this poses no risk and can be safely deprioritized. For those affected, patch within standard maintenance windows to minimize service disruption from the update itself.

Risk score, explained

The CVSS 3.1 score of 5.5 (MEDIUM) reflects a vulnerability with low attack complexity and no privileges required beyond standard user level, but mandatory local access and no confidentiality or integrity impact—only availability impact (kernel crash). The score appropriately captures that this is a local denial-of-service condition rather than a remote code execution or privilege escalation. The lack of KEV designation indicates this is not yet being actively weaponized at scale, which aligns with a MEDIUM rather than HIGH severity.

Frequently asked questions