CVE-2010-4210 in FreeBSD
Summary
by MITRE
The pfs_getextattr function in FreeBSD 7.x before 7.3-RELEASE and 8.x before 8.0-RC1 unlocks a mutex that was not previously locked, which allows local users to cause a denial of service (kernel panic), overwrite arbitrary memory locations, and possibly execute arbitrary code via vectors related to opening a file on a file system that uses pseudofs.
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Analysis
by VulDB Data Team • 01/20/2025
The vulnerability identified as CVE-2010-4210 represents a critical flaw in the FreeBSD operating system's kernel implementation of the pfs_getextattr function. This issue affects FreeBSD versions 7.x prior to 7.3-RELEASE and 8.x prior to 8.0-RC1, creating a dangerous race condition within the kernel's mutex management system. The flaw manifests when a local attacker interacts with filesystems utilizing pseudofs, a virtual filesystem implementation that provides a way to present information about the system in a hierarchical directory structure.
The technical root cause of this vulnerability lies in improper mutex handling within the kernel's file attribute retrieval mechanism. Specifically, the pfs_getextattr function attempts to unlock a mutex that was never properly locked in the first place, creating a fundamental violation of kernel synchronization principles. This improper mutex management creates a scenario where the kernel's memory management becomes corrupted, leading to unpredictable behavior that can manifest as kernel panics or memory corruption. The flaw operates at the kernel level, making it particularly dangerous as it bypasses normal user-space security boundaries and operates with the highest privilege levels available to the system.
The operational impact of this vulnerability extends beyond simple denial of service, presenting local attackers with the potential for arbitrary code execution and memory overwrite capabilities. When an attacker opens a file on a pseudofs filesystem, the flawed mutex handling can trigger a cascade of memory corruption events that may allow the attacker to manipulate kernel memory directly. This presents a severe security risk as it can enable privilege escalation and system compromise without requiring external network access or complex exploitation techniques. The vulnerability's local nature means that any user with access to the system can potentially exploit it, making it particularly dangerous in multi-user environments where system integrity is paramount.
From a cybersecurity perspective, this vulnerability maps directly to CWE-116, which describes improper mutex handling, and aligns with ATT&CK techniques involving privilege escalation and system compromise. The flaw demonstrates poor defensive programming practices and highlights the critical importance of proper synchronization mechanisms in kernel code. The exploitability of this vulnerability is relatively straightforward, requiring only local access and basic file system operations, yet the potential consequences are severe enough to warrant immediate attention. Organizations running affected FreeBSD versions should prioritize patching to prevent exploitation, as the vulnerability can be leveraged for both system instability and potential full system compromise, making it a high-priority remediation item in any security operations center's vulnerability management program.