CVE-2026-63838 in Linux
Summary
by MITRE • 07/19/2026
In the Linux kernel, the following vulnerability has been resolved:
ASoC: rsnd: Fix potential out-of-bounds access of component_dais[]
component_dais[RSND_MAX_COMPONENT] is initially zero-initialized
and later populated in rsnd_dai_of_node(). However, the existing boundary check: if (i >= RSND_MAX_COMPONENT)
does not guarantee that the last valid element remains zero. As a result, the loop can rely on component_dais[RSND_MAX_COMPONENT] being zero,
which may lead to an out-of-bounds access.
Found by Linux Verification Center (linuxtesting.org) with SVACE.
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Analysis
by VulDB Data Team • 07/19/2026
This vulnerability resides within the Linux kernel's sound subsystem, specifically in the Renesas Sound driver component known as ASoC rsnd. The issue manifests as a potential out-of-bounds memory access that could compromise system stability and security. The flaw occurs in the dai (Digital Audio Interface) component management where the component_dais array is initialized with zero values but subsequently populated during device tree parsing operations.
The technical root cause involves improper boundary validation within the driver's initialization logic. While component_dais[RSND_MAX_COMPONENT] is initially set to zero through zero-initialization, the subsequent population process in rsnd_dai_of_node() does not maintain this guarantee for the final array element. The existing boundary check condition if (i >= RSND_MAX_COMPONENT) fails to prevent access to memory beyond the intended array bounds, creating a scenario where the driver might attempt to read or write to component_dais[RSND_MAX_COMPONENT] as if it were a valid element.
This vulnerability represents a classic buffer over-read condition that aligns with CWE-129, which addresses insufficient validation of length of inputs to buffers. The flaw allows for potential information disclosure or system instability when the driver processes audio interface configurations through device tree nodes. The issue was discovered through systematic static analysis by the Linux Verification Center using SVACE tools, highlighting the importance of comprehensive testing in kernel security.
The operational impact of this vulnerability extends beyond simple memory corruption, as it could enable attackers to manipulate audio subsystem behavior or potentially escalate privileges within the kernel space. When the driver encounters certain device tree configurations, it may traverse into invalid memory regions, leading to unpredictable system behavior including potential crashes or data leakage. The vulnerability affects systems using Renesas SoC audio hardware where the rsnd driver is active, particularly in embedded and automotive applications where audio processing is critical.
Mitigation strategies should focus on implementing proper boundary validation and ensuring that all array accesses are strictly confined within allocated memory regions. The fix requires modifying the existing boundary check to properly validate that array indices do not exceed the actual usable array size, rather than relying on the assumption that the final element will remain zero. Additionally, developers should implement defensive programming practices such as bounds checking before any array access operations and consider using kernel-provided safe array access functions. This vulnerability demonstrates the critical importance of rigorous input validation in kernel drivers and aligns with ATT&CK technique T1068 which covers exploiting legitimate credentials through privilege escalation mechanisms. The fix should also include enhanced testing procedures to validate device tree parsing scenarios and ensure that all memory accesses remain within defined boundaries throughout the driver's operational lifecycle.