CVE-2026-31619: Linux Kernel Array Lookup Vulnerability

CVE-2026-31619 Overview

A vulnerability has been identified in the Linux kernel's ALSA (Advanced Linux Sound Architecture) fireworks driver that allows an out-of-bounds array access when processing device-supplied status values. The flaw exists in the EFW (Echo Fireworks) response handling code where a 32-bit status field supplied by a firewire device is used as an index into the efr_status_names[] string array without proper bounds checking.

The efr_status_names[] array contains only 17 entries, but the device-supplied status value can be any 32-bit value, including EFR_STATUS_INCOMPLETE (0x80000000). When an out-of-bounds status value is used for string lookup, the code accesses memory outside the array bounds, potentially leading to system instability or denial of service conditions.

Critical Impact
A local attacker with access to firewire devices could trigger an out-of-bounds memory read, potentially causing kernel crashes or information disclosure from kernel memory.

Affected Products

Linux Linux Kernel

Discovery Timeline

2026-04-24 - CVE CVE-2026-31619 published to NVD
2026-04-28 - Last updated in NVD database

Technical Details for CVE-2026-31619

Vulnerability Analysis

This vulnerability stems from insufficient input validation when processing responses from firewire audio devices using the Echo Fireworks protocol. The ALSA fireworks driver handles communication with firewire-connected audio interfaces and processes status responses from these devices.

When a device returns a status value in its EFW response, the driver uses this value to index into the efr_status_names[] array for logging or display purposes. Since the status field is a 32-bit value directly supplied by the device hardware, it can contain any arbitrary value. The array only has 17 valid entries (indices 0-16), meaning any status value of 17 or greater results in an out-of-bounds access.

Of particular concern is the EFR_STATUS_INCOMPLETE status code, which has a value of 0x80000000. When this status is returned and used as an array index, the resulting memory access occurs far outside the bounds of the legitimate array, reading from arbitrary kernel memory locations.

Root Cause

The root cause is the absence of bounds checking on the device-supplied status value before using it as an array index. The code implicitly trusted the device response data without validating that the status value falls within the valid range of the efr_status_names[] array. This represents a classic improper input validation vulnerability where externally-supplied data is used directly without sanitization.

Attack Vector

Exploitation requires local access and the ability to connect or control a malicious or compromised firewire device. An attacker could craft a firewire device (or modify an existing device's firmware) to return arbitrary status values in EFW responses. When the kernel driver processes these malformed responses, the out-of-bounds array access occurs during the status string lookup.

The attack vector is local, requiring physical access to connect a firewire device or control over an already-connected device. While this limits the attack surface, systems with firewire ports in physically accessible locations or those processing data from untrusted firewire devices are at risk.

The fix implements proper bounds checking by validating the status index against the array size before performing the lookup. If the status value is outside the valid range, the driver now returns "unknown" rather than accessing invalid memory.

Detection Methods for CVE-2026-31619

Indicators of Compromise

Unexpected kernel oops or panic messages referencing the ALSA fireworks driver or snd_efw module
Kernel log entries showing unusual firewire device activity or malformed EFW responses
System crashes correlated with firewire device connections or audio subsystem operations

Detection Strategies

Monitor kernel logs (dmesg) for warnings or errors related to the snd-fireworks or snd_efw kernel modules
Implement kernel crash dump analysis to identify stack traces involving the fireworks driver
Deploy host-based intrusion detection to alert on unexpected firewire device activity

Monitoring Recommendations

Enable kernel auditing for device plug events, particularly firewire/IEEE 1394 devices
Configure crash reporting to capture and analyze kernel panics for patterns indicative of this vulnerability
Review system logs for any EFW-related error messages that may indicate exploitation attempts

How to Mitigate CVE-2026-31619

Immediate Actions Required

Apply the latest kernel security patches that include the bounds checking fix for the fireworks driver
Disable or unload the snd-fireworks kernel module on systems that do not require firewire audio support
Restrict physical access to firewire ports on affected systems until patching is complete

Patch Information

Linux kernel maintainers have released patches across multiple stable kernel branches to address this vulnerability. The fix properly bounds the device-supplied status index against the efr_status_names[] array size and prints "unknown" for unrecognized status values.

Patches are available from the following kernel git commits:

Workarounds

Blacklist the snd-fireworks module by adding blacklist snd-fireworks to /etc/modprobe.d/blacklist.conf
Physically disable firewire ports in BIOS/UEFI settings if the functionality is not required
Unload the module from running systems using modprobe -r snd-fireworks if no firewire audio devices are in use

bash

# Disable the fireworks module to mitigate the vulnerability
echo "blacklist snd-fireworks" | sudo tee /etc/modprobe.d/blacklist-fireworks.conf
sudo modprobe -r snd-fireworks