CVE-2025-38729 in Linux
Summary
by MITRE • 09/04/2025
In the Linux kernel, the following vulnerability has been resolved:
ALSA: usb-audio: Validate UAC3 power domain descriptors, too
UAC3 power domain descriptors need to be verified with its variable bLength for avoiding the unexpected OOB accesses by malicious firmware, too.
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Analysis
by VulDB Data Team • 02/10/2026
The vulnerability identified as CVE-2025-38729 affects the Linux kernel's Advanced Linux Sound Architecture implementation specifically within the usb-audio subsystem. This issue represents a critical out-of-bounds memory access vulnerability that could potentially allow malicious firmware to execute arbitrary code or cause system instability. The flaw exists in the handling of USB Audio Class 3.0 (UAC3) power domain descriptors, which are used to define power management configurations for USB audio devices. The vulnerability stems from insufficient validation of descriptor lengths, creating a potential attack surface where malformed firmware could trigger memory corruption through improper bounds checking.
The technical implementation of this vulnerability occurs within the kernel's USB audio driver where UAC3 power domain descriptors are processed without adequate validation of their bLength field. This field specifies the size of the descriptor in bytes, yet the current implementation fails to verify that the descriptor data does not exceed the declared length. When malicious firmware provides descriptors with invalid length specifications, the kernel's audio subsystem may attempt to read beyond allocated memory boundaries, leading to potential buffer overflows or other memory corruption issues. This type of vulnerability falls under CWE-129 Input Validation and is classified as a memory safety issue that could enable privilege escalation or denial of service conditions.
The operational impact of this vulnerability extends beyond simple system crashes or hangs, as it represents a potential entry point for sophisticated attacks targeting embedded systems or devices running Linux with USB audio capabilities. Attackers could potentially exploit this through malicious USB audio devices or firmware updates that manipulate power domain descriptors during device enumeration. The vulnerability affects systems where USB audio devices are actively used, particularly in professional audio equipment, embedded systems, and IoT devices that rely on Linux kernel audio subsystems. According to ATT&CK framework, this vulnerability could be leveraged as part of a broader attack chain under techniques such as privilege escalation or resource exhaustion, where an attacker might use the memory corruption to gain elevated privileges or disrupt system operations.
Mitigation strategies for CVE-2025-38729 should focus on implementing proper bounds checking for all UAC3 power domain descriptors before processing their contents. System administrators should ensure that kernel updates are applied promptly, as this vulnerability has been addressed in recent kernel versions through enhanced validation routines. Additional protective measures include implementing device whitelisting for USB audio devices, disabling unnecessary USB audio functionality in embedded systems, and monitoring for unusual USB device enumeration patterns. The fix typically involves adding explicit length validation checks that verify the bLength field against the actual descriptor data size before any memory access operations occur, thereby preventing the out-of-bounds reads that could be exploited by malicious firmware. Organizations should also consider implementing runtime protection mechanisms and regular security audits of their USB audio device configurations to minimize exposure to similar vulnerabilities.