CVE-2024-53197

What it actually does

This is a Linux kernel memory-corruption flaw in the USB audio handling path. A malicious or malformed USB device can report an abnormal bNumConfigurations value that is larger than the value used when allocating the kernel's USB configuration array. Later cleanup and parsing paths, including usb_destroy_configuration, may access entries beyond the allocated dev->config structure. Because this occurs in kernel context, the most likely impacts are kernel crash, denial of service, and potentially privilege escalation or kernel-code execution if an attacker can shape memory reliably.

Why it matters to the business

Systems that allow untrusted USB devices, USB passthrough, docking stations, peripheral sharing, or virtualized USB redirection may be exposed to compromise or outage from a malicious USB audio-like device. The issue is listed in CISA KEV with known exploitation and had a remediation deadline of 2025-04-30, so unpatched systems should be treated as overdue and higher priority despite the moderate EPSS score of 0.03558. Operational risk is highest for workstations, shared terminals, engineering systems, kiosks, conference-room devices, and servers where physical or redirected USB access is possible.

How an attack unfolds

An attacker needs a path to present a crafted USB device to a vulnerable Linux system, either through physical access, a malicious peripheral, a compromised docking station, USB-over-IP, hypervisor USB passthrough, or another mechanism that makes the host enumerate attacker-controlled USB descriptors. The device advertises malformed configuration metadata, specifically a bNumConfigurations value that causes the kernel to allocate one size but later iterate or destroy configuration entries as if more entries existed. When the USB core or ALSA usb-audio code processes or tears down the device, the kernel performs out-of-bounds memory access. In practice this can crash the machine and, depending on kernel build, heap layout, mitigations, and exploit reliability, may be chained with other local techniques for privilege escalation. The provided threat context references broader zero-day and Linux privilege-escalation activity; however, this vulnerability's exploitation artifacts are primarily host USB enumeration and kernel-fault evidence rather than network indicators.

How to fix it

Apply the Linux kernel updates from the relevant distribution or kernel vendor that include the ALSA usb-audio / USB configuration bounds fix for this vulnerability. Because the supplied affected-product metadata lists Ubuntu 14.04 flashplugin-nonfree fixed in 11.2.202.632ubuntu0.14.04.1, ensure that package is updated if it is in scope; however, do not treat that package update alone as remediation for the kernel flaw described here. The primary remediation is a patched kernel and reboot into that kernel. Where immediate patching is not possible, reduce exposure by disabling or restricting untrusted USB devices, disabling USB audio support if operationally feasible, blocking USB passthrough into virtual machines, preventing USB-over-IP attachment from untrusted sources, enforcing physical port controls, and monitoring for unexpected USB audio device enumeration.

How to confirm the fix worked

Confirm systems are running a vendor kernel version that explicitly includes the fix, not merely that an update package was installed. Validate with package inventory, kernel version checks, and reboot status checks so the active kernel matches the patched kernel. On Debian/Ubuntu-style systems, compare uname -r and the installed linux-image package against the vendor advisory; also confirm whether snd_usb_audio is loaded with lsmod if assessing exposure. If tracking the supplied package metadata, verify flashplugin-nonfree is at least 11.2.202.632ubuntu0.14.04.1 on Ubuntu 14.04 systems, while separately validating the kernel. Review dmesg or journalctl after testing with normal USB audio devices to ensure there are no kernel warnings, KASAN findings, or crashes in usb_get_configuration, usb_destroy_configuration, or snd_usb_audio paths.

Typical attack path

1. Attacker obtains physical, virtual, or redirected USB access to a target Linux system.
2. Attacker connects or presents a crafted USB device that emulates an affected USB audio device class or otherwise reaches the vulnerable USB configuration parsing path.
3. The device supplies a malformed bNumConfigurations value that exceeds the allocation assumptions used by the kernel.
4. The Linux USB core and ALSA usb-audio paths enumerate, parse, or later destroy the device configuration data.
5. The kernel performs an out-of-bounds access in USB configuration handling.
6. The attacker causes a kernel crash or attempts to shape memory corruption for privilege escalation or arbitrary kernel execution.

How to detect it

To determine whether exploitation may already have occurred, review kernel logs, system journals, crash dumps, EDR telemetry, USB device inventory logs, hypervisor USB passthrough logs, and physical-access events. Focus on crashes or kernel warnings that coincide with USB insertion, USB audio enumeration, docking-station events, or USB redirection. Search for unexpected Creative Extigy, Mbox, generic USB audio, or malformed-device enumeration immediately before kernel oops, panic, KASAN, slab, or general-protection-fault messages. On Linux systems, useful sources include /var/log/kern.log, /var/log/syslog, journalctl -k, audit logs for device attachment if configured, /var/crash, kdump/vmcore artifacts, and EDR records that capture kernel panic or device events. There are no reliable network IOCs for this issue because exploitation is typically local or peripheral-based.

• usb_destroy_configuration
• usb_get_configuration
• snd_usb_audio
• snd-usb-audio
• ALSA: usb-audio
• bNumConfigurations
• KASAN: slab-out-of-bounds
• KASAN: out-of-bounds
• BUG: unable to handle kernel paging request
• general protection fault
• kernel NULL pointer dereference
• kernel panic
• Oops:
• Product: Extigy
• Product: Mbox
• /var/log/kern.log
• /var/log/syslog
• /var/crash
• vmcore

What your security team should do

• Prioritize patching and rebooting Linux systems with physical USB exposure, USB passthrough, shared peripherals, or USB audio enabled; the KEV remediation date has passed.
• Temporarily block untrusted USB device attachment and disable USB passthrough or USB-over-IP for sensitive systems until patched.
• Hunt for historical kernel crashes, KASAN reports, or unusual USB audio enumeration events involving Extigy, Mbox, snd_usb_audio, usb_get_configuration, or usb_destroy_configuration.
• Inventory systems that load snd_usb_audio or routinely accept external USB peripherals, including workstations, kiosks, lab systems, and virtualization hosts.
• Ensure vulnerability management rules distinguish the underlying Linux kernel flaw from the supplied flashplugin-nonfree package metadata and do not close the finding based only on the non-kernel package.
• Capture and preserve kernel logs, crash dumps, and USB device metadata for any suspicious crash temporally associated with USB insertion or device redirection.