CVE-2026-53307

What it actually does

This vulnerability is a Linux kernel denial-of-service flaw in the generic pin controller configuration parser. When a device tree node contains a present but empty `pinmux` property, the kernel path that parses pin multiplexing data assumes the property has a valid non-zero length. That can cause the allocator to return a special zero-size allocation value rather than a normal buffer, and later code may dereference invalid memory. The likely result is a kernel oops, panic, or device crash during boot, driver probe, or device-tree overlay application. The issue does not inherently provide code execution or privilege escalation; the primary impact is availability loss.

Why it matters to the business

Systems that rely on Linux device trees, especially embedded, appliance, ARM, industrial, IoT, and hardware-controller platforms, may crash or fail to boot if they consume a malformed or malicious device-tree configuration. Operational impact can include device outages, failed firmware updates, service interruption, truck rolls for remote appliances, and loss of hardware control functions. Public exploit maturity is currently listed as none, EPSS is very low, and it is not in CISA KEV, so broad internet-scale exploitation is unlikely; however, the risk is higher where untrusted users, update mechanisms, plug-in hardware, or privileged management interfaces can influence device-tree blobs or overlays.

How an attack unfolds

An attacker needs a path to make the affected kernel parse a malformed device-tree `pinmux` property. In a typical scenario, the attacker first gains the ability to modify a device-tree blob, boot configuration, firmware package, or device-tree overlay, or abuses a management/update path that accepts such content. They then craft a device-tree node containing a `pinmux` property that exists but has zero length. When the system boots, probes the affected hardware, or dynamically applies the overlay, the kernel invokes the generic pinctrl parser. Because vulnerable kernels do not fully validate the property length, the parser can treat a zero-length allocation as usable memory and crash when it is accessed. The attacker’s end result is denial of service: the device may panic, reboot, hang, or fail to complete boot until the malformed configuration is removed or the kernel is updated.

How to fix it

Upgrade to a Linux kernel build that includes the upstream fix for `pinctrl: pinconf-generic: Fully validate 'pinmux' property`. Because no product-specific fixed versions were provided, use the fixed kernel version supplied by the operating-system, appliance, embedded BSP, SoC vendor, or distribution maintainer. For embedded products, ensure the fix is incorporated into the vendor kernel tree and all firmware images that ship a kernel. As mitigations, restrict who can modify bootloader configuration, device-tree blobs, overlays, and firmware packages; disable or tightly control runtime device-tree overlay loading where not required; enforce signed firmware and signed boot artifacts; and validate device-tree sources/blobs in CI so that `pinmux` properties are non-empty and correctly sized.

How to confirm the fix worked

Confirm exposure by checking whether deployed kernels include the upstream pinconf-generic validation fix. Review vendor advisories, kernel package changelogs, or source trees for the patch titled `pinctrl: pinconf-generic: Fully validate 'pinmux' property`. On systems using custom kernels, inspect the relevant pinctrl generic parser code and verify that the `pinmux` property length is explicitly validated before allocation and dereference. Validate configuration artifacts by decompiling device-tree blobs with `dtc` and searching for `pinmux;` or otherwise empty `pinmux` properties. After remediation, boot representative hardware and apply any supported overlays while monitoring `dmesg`/kernel logs for pinctrl parsing errors, oopses, or panics.

Typical attack path

1. Identify a Linux-based target that uses device-tree pin controller configuration.
2. Obtain a way to influence device-tree data, such as firmware modification, bootloader access, a privileged local account, an update package path, or device-tree overlay loading.
3. Create or modify a device-tree node so that the `pinmux` property is present but empty.
4. Trigger parsing by rebooting the system, loading the overlay, or causing the relevant pinctrl driver to probe.
5. The vulnerable kernel dereferences invalid memory while parsing the malformed property.
6. The system crashes, reboots, hangs, or fails to boot, causing denial of service.

How to detect it

To determine whether this was already exploited or triggered, review kernel logs, persistent journal logs, serial console output, crash dumps, watchdog reset records, bootloader logs, and firmware/update audit logs. Focus on crashes occurring immediately after firmware updates, boot configuration changes, device-tree overlay application, new hardware attachment, or driver probing. Look for kernel oops or panic traces involving pinctrl, pin configuration, device-tree parsing, or `pinconf_generic_parse_dt_pinmux`. Examine `/boot`, firmware partitions, overlay directories, and update packages for recently changed device-tree blobs or overlays. Decompile suspicious `.dtb` or `.dtbo` files with `dtc` and search for empty `pinmux` properties. Correlate system reboots, watchdog resets, and failed boots with administrative actions or update processes that modified device-tree artifacts.

• pinconf_generic_parse_dt_pinmux
• pinctrl: pinconf-generic
• pinconf-generic
• pinmux;
• pinmux = <>
• Unable to handle kernel NULL pointer dereference
• Kernel panic - not syncing
• Oops:
• BUG: kernel NULL pointer dereference
• Internal error: Oops
• watchdog: watchdog did not stop
• /boot/*.dtb
• /boot/*.dtbo
• /lib/firmware/*.dtb
• /lib/firmware/*.dtbo
• /sys/kernel/config/device-tree/overlays

What your security team should do

• Inventory Linux systems that use device-tree based hardware description, prioritizing embedded appliances, ARM platforms, industrial devices, network appliances, and products that support runtime device-tree overlays.
• Coordinate with OS, hardware, SoC, and appliance vendors to obtain kernel builds containing the pinconf-generic `pinmux` validation fix.
• For custom or vendor-maintained kernels, backport the upstream patch and include it in the next firmware or kernel maintenance release.
• Restrict modification of device-tree blobs, boot partitions, firmware images, bootloader variables, and overlay directories to trusted administrative/update processes only.
• Require cryptographic signing and verification for firmware, boot images, device-tree blobs, and overlays where supported.
• Scan device-tree source and compiled blobs for empty `pinmux` properties before release or deployment.
• Monitor kernel logs for oops, panic, or pinctrl parser failures following firmware updates, overlay changes, or hardware configuration changes.
• Treat unexpected repeated reboot loops or boot failures on affected device classes as potentially malicious or malformed hardware-configuration input until ruled out.