CVE-2026-53024

What it actually does

This flaw is a use-after-free in the Linux kernel Greybus raw character device handling. When a Greybus connection is disconnected, the connection object can be freed while a later or concurrent write operation still attempts to use it. That stale pointer can cause a NULL pointer dereference or invalid memory access in kernel context, leading to a kernel panic. The demonstrated impact is local denial of service through system crash; reliable privilege escalation is not indicated by the available information.

Why it matters to the business

Systems using the Linux Greybus raw interface may be crashable by a local user or process with access to the affected character device, causing service interruption, node reboot, workload disruption, and potential availability issues for embedded, development, or specialized hardware environments that rely on Greybus. The EPSS score is currently very low and it is not listed in CISA KEV, so broad internet-scale exploitation is unlikely, but exposed multi-user systems or devices granting access to Greybus character devices should still prioritize remediation.

How an attack unfolds

An attacker first needs local ability to interact with the Greybus raw character device, typically by having access to the relevant device node or by compromising a process that already has that access. The attacker triggers or waits for a Greybus disconnect event that destroys the underlying connection object. After disconnect, the attacker writes to the raw character device. Because the write path can pass the previously freed connection object into Greybus operation creation and synchronous operation handling, the kernel dereferences invalid state and panics. The attack outcome is generally a local kernel crash and denial of service rather than remote code execution.

How to fix it

Apply the Linux kernel update that includes the Greybus raw synchronization fix for this issue. If vendor kernels are used, upgrade to the distribution, appliance, or device-vendor kernel release that backports the patch. Where immediate patching is not possible, reduce exposure by unloading or disabling unused Greybus-related modules such as gb_raw where operationally safe, restricting permissions on Greybus character devices, preventing untrusted local users or containers from accessing device nodes, and limiting hotplug/disconnect control to trusted components. No product-specific fixed versions were provided in the input, so remediation should be tracked through the relevant Linux distribution or device vendor advisory for CVE-2026-53024.

How to confirm the fix worked

Confirm that the running kernel package or vendor build includes the Greybus raw fix for write-after-disconnect synchronization. Validate by checking the vendor advisory, kernel changelog, or source tree for the patch that adds locking around raw write and disconnect paths to prevent use of a destroyed Greybus connection. On systems where Greybus is not needed, verify that Greybus raw modules are not loaded and that related device nodes are absent or inaccessible to untrusted users. After patching, confirm the host is booted into the updated kernel, not merely that the package is installed.

Typical attack path

1. Gain local execution or control of a process on a Linux system with the Greybus raw kernel module/interface available.
2. Obtain permission to write to the Greybus raw character device.
3. Trigger, race, or wait for a Greybus disconnect that destroys the connection object.
4. Write to the character device after disconnect.
5. Cause the kernel write path to use the freed Greybus connection object.
6. Crash the kernel, causing denial of service or system reboot.

How to detect it

Look for evidence of kernel panics, oops reports, or unexpected reboots involving the Greybus raw module and write operations after disconnect events. Relevant sources include kernel logs, journald, /var/log/kern.log, /var/log/messages, persistent crash dumps, kdump/vmcore analysis, systemd journal boot history, and EDR telemetry that records kernel crashes or module activity. Search for stack traces containing raw_write, gb_operation_create_common, gb_operation_sync_timeout, gb_connection_destroy, or the gb_raw module. Also review audit or device access logs, where available, for processes writing to Greybus character devices shortly before a crash. Because this vulnerability primarily causes a crash, forensic evidence may be limited to pre-reboot kernel logs and crash dumps; absence of logs after a hard panic does not prove absence of exploitation.

• BUG: kernel NULL pointer dereference, address: 0000000000000218
• gb_operation_create_common
• gb_operation_create_flags
• gb_operation_sync_timeout
• raw_write
• [gb_raw]
• gb_connection_destroy
• greybus: raw
• kernel panic
• Oops:
• Call Trace:
• vfs_write
• ksys_write
• entry_SYSCALL_64_after_hwframe
• /var/log/kern.log
• /var/log/messages
• /proc/vmcore

What your security team should do

• Inventory Linux systems and embedded devices where Greybus support or the gb_raw module is enabled.
• Prioritize patching systems that allow local shell access, run untrusted workloads, expose device nodes to containers, or use Greybus-connected hardware.
• Restrict write access to Greybus raw character devices to only trusted administrative or service accounts.
• Disable or blacklist unused Greybus raw functionality where it is not required.
• Review kernel crash logs for Greybus-related panics to determine whether the issue may already have been triggered.
• Ensure monitoring alerts on unexpected kernel panics, reboots, and oops messages involving gb_raw or Greybus functions.
• Track Linux distribution and device-vendor advisories for the exact fixed kernel versions applicable to deployed platforms.