CVE-2007-6761 in Linux
Summary
by MITRE
drivers/media/video/videobuf-vmalloc.c in the Linux kernel before 2.6.24 does not initialize videobuf_mapping data structures, which allows local users to trigger an incorrect count value and videobuf leak via unspecified vectors, a different vulnerability than CVE-2010-5321.
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Analysis
by VulDB Data Team • 08/19/2025
The vulnerability identified as CVE-2007-6761 resides within the Linux kernel's video buffer management subsystem, specifically in the videobuf-vmalloc.c driver file. This flaw affects kernel versions prior to 2.6.24 and represents a critical memory management issue that can be exploited by local attackers to manipulate video buffer data structures. The vulnerability stems from improper initialization of videobuf_mapping data structures, creating a condition where the kernel fails to correctly track buffer mappings and their associated reference counts. This misconfiguration enables attackers to manipulate the internal accounting of video buffer allocations and deallocations, potentially leading to memory corruption and system instability.
The technical implementation of this vulnerability involves the improper initialization of memory management structures within the videobuf subsystem that handles video buffer allocation for kernel drivers. When video buffers are allocated through the vmalloc interface, the kernel's videobuf_mapping data structures are not properly initialized with default values, particularly concerning reference counting mechanisms and memory mapping information. This initialization failure creates a scenario where the kernel maintains incorrect internal state information about buffer usage, allowing malicious processes to exploit this inconsistency to perform unauthorized operations on video buffer resources. The vulnerability is particularly concerning because it operates at the kernel level, where such flaws can lead to privilege escalation or system compromise.
The operational impact of CVE-2007-6761 extends beyond simple memory leaks, as it can enable a range of malicious activities including denial of service conditions and potential privilege escalation. Local attackers can leverage this vulnerability to cause incorrect reference counting in the videobuf subsystem, leading to memory allocation inconsistencies that may result in buffer overflows, use-after-free conditions, or other memory corruption scenarios. The vulnerability's exploitation potential is heightened by the fact that it affects core kernel components that are actively used in multimedia processing and video capture operations. This creates a realistic attack surface where malicious users could manipulate video buffer management to cause system crashes or potentially gain elevated privileges within the kernel space.
From a cybersecurity perspective, this vulnerability aligns with CWE-457: Use of Uninitialized Variable, which specifically addresses the risks associated with uninitialized data structures in kernel code. The flaw also relates to ATT&CK technique T1068: Exploitation for Privilege Escalation, as local attackers can exploit kernel memory management inconsistencies to gain elevated system privileges. Additionally, the vulnerability demonstrates characteristics consistent with T1499.004: Endpoint Denial of Service, where improper resource management can lead to system instability and denial of service conditions. The root cause of this vulnerability highlights the critical importance of proper initialization practices in kernel code development, particularly for memory management subsystems that handle critical resources used by multimedia applications and hardware drivers.
Mitigation strategies for CVE-2007-6761 primarily focus on applying the appropriate kernel security patches and updates that address the uninitialized variable issue in the videobuf subsystem. System administrators should prioritize upgrading to kernel versions 2.6.24 or later where this vulnerability has been resolved through proper initialization of the videobuf_mapping data structures. Organizations should also implement monitoring solutions to detect unusual patterns in video buffer allocation and deallocation activities that might indicate exploitation attempts. Additional defensive measures include restricting local user access to multimedia applications that utilize affected kernel drivers and implementing proper kernel hardening techniques such as kernel address space layout randomization and stack canaries. The vulnerability serves as a reminder of the importance of thorough code review processes for kernel developers and the necessity of comprehensive testing for memory management subsystems that handle critical system resources.