CVE-2026-53257

What it actually does

This flaw is a Linux kernel wireless-stack denial-of-service issue in cfg80211/mac80211. The kernel could enter an inconsistent Wi-Fi capability state when Extremely High Throughput or High Efficiency capability elements were present without the corresponding operation elements. In affected kernels, that inconsistent state could cause mac80211 to crash, potentially resulting in a kernel panic, wireless subsystem failure, or full system reboot depending on kernel configuration and error handling. The issue affects availability rather than confidentiality or integrity; there is no indication from the provided data that it enables privilege escalation or code execution.

Why it matters to the business

Systems that rely on Linux Wi-Fi functionality could experience unexpected outages or reboots if the vulnerable wireless code path is triggered. The operational impact is highest for Linux-based access points, routers, embedded devices, laptops, industrial gateways, and appliances using cfg80211/mac80211 with modern Wi-Fi features. Public exploitation likelihood appears low at this time: EPSS is 0.001, it is not listed in CISA KEV, it is not known to be used in ransomware campaigns, and no exploit maturity is reported. However, because this is kernel-level code, a successful trigger can disrupt the entire host rather than only a user-space service.

How an attack unfolds

An attacker would need a way to make the Linux wireless subsystem process an inconsistent HE/EHT configuration where a capability element is provided without the matching operation element. The most plausible exploitation path is through local or adjacent control of Wi-Fi configuration, such as a process or component that can submit crafted cfg80211/nl80211 wireless settings, or a buggy or malicious wireless management component that produces inconsistent wireless information elements. Once the malformed state is accepted by the vulnerable kernel, mac80211 may dereference or process assumptions that are no longer valid, causing a crash. There is no evidence in the supplied data of broad remote exploitation, active exploitation, ransomware use, or named threat actor activity.

How to fix it

Apply the vendor-provided Linux kernel update that includes the cfg80211 fix enforcing consistency between HE/EHT capability and operation elements. Because no exact affected products or fixed package versions were provided, use the relevant Linux distribution, appliance, or device vendor advisory to identify the corrected kernel package for each platform. After installing the fixed kernel, reboot systems to ensure the patched kernel is running. Where immediate patching is not possible, reduce exposure by disabling unused Wi-Fi interfaces, unloading unnecessary wireless kernel modules where operationally safe, limiting local administrative access to wireless configuration tooling, and avoiding untrusted or experimental Wi-Fi management components that can manipulate HE/EHT settings.

How to confirm the fix worked

Confirm that each system is running a kernel build that contains the cfg80211 consistency fix, not merely that the package is installed. Validate with the running kernel version, distribution package metadata, and the relevant vendor advisory. On systems with Wi-Fi enabled, confirm that cfg80211/mac80211 modules are either patched or not loaded if Wi-Fi is not required. If safe in a test environment, attempt to submit or simulate inconsistent HE/EHT capability and operation data and verify that the kernel rejects it cleanly rather than crashing. Review recent kernel logs for mac80211/cfg80211 crashes before and after remediation to confirm that the failure condition is no longer occurring.

Typical attack path

1. Identify a Linux system using the cfg80211/mac80211 wireless stack with HE or EHT Wi-Fi capability support.
2. Obtain a position that can influence wireless configuration or wireless management inputs, such as local administrative control, compromised Wi-Fi management software, or another path that can submit crafted nl80211/cfg80211 settings.
3. Provide inconsistent wireless capability/operation data, specifically setting HE/EHT capability information without the required matching operation information.
4. Trigger the affected mac80211 code path by starting, changing, or processing the wireless interface configuration.
5. Cause the kernel wireless subsystem to crash, potentially resulting in loss of Wi-Fi service or a full host denial of service.

How to detect it

Look for evidence of prior denial-of-service activity rather than post-exploitation artifacts, because this issue is a crash condition and no malware, persistence, or data-theft indicators are implied by the provided information. Review kernel logs, system journals, crash dumps, panic logs, watchdog reset records, and uptime/reboot history for events involving cfg80211, mac80211, nl80211, HE, EHT, or Wi-Fi interface reconfiguration shortly before a crash or reboot. Useful sources include journalctl/kern.log/dmesg, /var/log/kern.log, /var/log/messages, systemd journal, kdump/vmcore records, appliance crash logs, and hypervisor or out-of-band management reset events. Correlate crashes with local invocations of wireless configuration utilities, access point daemon activity, driver reloads, or configuration changes. In SIEM, search for kernel oops, panic, null pointer dereference, and call traces containing cfg80211/mac80211 symbols. Absence of these artifacts does not prove non-exploitation if logs were rotated, the system rebooted without persistent logging, or crash dumps were disabled.

• cfg80211
• mac80211
• nl80211
• eht_cap
• eht_oper
• HE cap
• EHT cap
• HE/EHT
• BUG: kernel NULL pointer dereference
• kernel NULL pointer dereference
• Oops: 0000
• Kernel panic
• Call Trace:
• ieee80211
• hostapd
• wpa_supplicant
• /var/log/kern.log
• /var/log/messages
• /var/crash
• /proc/modules

What your security team should do

• Prioritize patching Linux systems that provide Wi-Fi access point, router, embedded gateway, kiosk, mobile, or appliance functionality, especially where availability is important.
• Inventory systems with loaded cfg80211, mac80211, or vendor Wi-Fi drivers and determine whether they are running kernels that include the fix.
• Reboot after kernel updates; live package installation alone does not remediate a running vulnerable kernel.
• Restrict access to tools and services that can configure wireless interfaces, such as host access to nl80211/cfg80211 management functions.
• Disable Wi-Fi functionality on systems where it is not required.
• Monitor kernel logs for wireless-stack crashes, null pointer dereferences, kernel oops events, and unexpected reboots involving cfg80211 or mac80211.
• Treat repeated unexplained Wi-Fi-related kernel crashes as potential exploitation or misconfiguration until logs and device state are reviewed.