CVE-2025-38679 in Linux
Summary
by MITRE • 09/04/2025
In the Linux kernel, the following vulnerability has been resolved:
media: venus: Fix OOB read due to missing payload bound check
Currently, The event_seq_changed() handler processes a variable number of properties sent by the firmware. The number of properties is indicated by the firmware and used to iterate over the payload. However, the payload size is not being validated against the actual message length.
This can lead to out-of-bounds memory access if the firmware provides a property count that exceeds the data available in the payload. Such a condition can result in kernel crashes or potential information leaks if memory beyond the buffer is accessed.
Fix this by properly validating the remaining size of the payload before each property access and updating bounds accordingly as properties are parsed.
This ensures that property parsing is safely bounded within the received message buffer and protects against malformed or malicious firmware behavior.
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Analysis
by VulDB Data Team • 02/10/2026
The vulnerability identified as CVE-2025-38679 represents a critical out-of-bounds read condition within the Linux kernel's venus media driver subsystem. This flaw exists in the event_seq_changed() handler which processes firmware-generated events containing variable-length property data structures. The vulnerability stems from inadequate validation of payload boundaries during the parsing process, creating a scenario where the kernel's memory management can be compromised through malformed firmware messages. The issue specifically affects the Qualcomm venus video decoder driver that handles multimedia processing in embedded systems and mobile devices. This type of vulnerability falls under the CWE-129 category of "Improper Validation of Array Index" and represents a classic buffer over-read condition that can lead to system instability and potential information disclosure.
The technical implementation of this vulnerability occurs when the firmware sends a message containing a property count field that indicates how many properties to process within the payload. However, the kernel code fails to validate whether the actual payload size can accommodate the number of properties specified by the firmware. During the iteration process, the code accesses memory locations beyond the allocated buffer boundaries, potentially reading uninitialized kernel memory or accessing memory regions belonging to other processes. This condition creates a dangerous attack surface where malicious firmware could exploit the missing bounds checking to cause kernel panics or extract sensitive information from kernel memory spaces. The vulnerability is particularly concerning because it operates at the kernel level where such faults can lead to complete system compromise.
The operational impact of this vulnerability extends beyond simple system crashes to potentially enable information leakage attacks that could expose sensitive kernel memory contents. When an out-of-bounds read occurs, the kernel may access memory locations that contain cryptographic keys, network credentials, or other confidential data. This represents a significant threat to system security, especially in mobile devices and embedded systems where the venus driver is commonly used for video processing tasks. The vulnerability can be exploited through malicious firmware updates or compromised device firmware, making it particularly dangerous in environments where firmware integrity cannot be guaranteed. Attackers could leverage this flaw to gain unauthorized access to system resources or cause persistent denial-of-service conditions that would require system reboot to resolve.
Mitigation strategies for CVE-2025-38679 should focus on implementing robust payload validation mechanisms within the venus driver's event processing code. The fix requires adding proper bounds checking before each property access operation, ensuring that the remaining payload size is sufficient to accommodate the next property before attempting to read it. This approach aligns with the ATT&CK framework's defense evasion techniques by preventing malicious code execution through memory corruption vulnerabilities. System administrators should prioritize updating affected kernel versions and implementing firmware integrity checks to prevent exploitation. Additionally, monitoring for unusual firmware behavior patterns and implementing kernel memory protection mechanisms such as stack canaries and memory sanitization tools can help detect and prevent exploitation attempts. The vulnerability highlights the importance of input validation in kernel drivers and demonstrates the critical need for comprehensive bounds checking in all firmware communication pathways.