CVE-2026-74330 in Linux
Summary
by MITRE • 08/15/2026
In the Linux kernel, the following vulnerability has been resolved:
configfs: fix lockless traversals of ->s_children
Having the parent directory locked protects entries from removal by another thread, but it does *not* protect cursors from being moved around by lseek() - or freed, for that matter.
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Analysis
by VulDB Data Team • 08/15/2026
The vulnerability identified in the Linux kernel relates to a race condition within the configfs filesystem implementation that affects how directory traversals are handled without locks. This issue specifically impacts the ->s_children structure which maintains references to directory entries within the configfs filesystem. The fundamental problem arises from the assumption that holding a lock on a parent directory provides sufficient protection for all operations involving its child entries, when in reality this locking mechanism fails to prevent concurrent modifications that can occur during cursor movement operations.
The technical flaw stems from the mismatch between the locking semantics and the actual operational requirements of the configfs implementation. When threads perform lseek() operations or other cursor manipulations on directory entries, they can effectively move or even free these entries while other threads may be traversing the same structure. This creates a scenario where a thread might access a memory location that has already been deallocated, leading to potential system crashes or arbitrary code execution. The vulnerability demonstrates a classic race condition pattern where concurrent access patterns create inconsistent states in shared data structures.
The operational impact of this vulnerability extends beyond simple stability concerns to potentially enable privilege escalation and system compromise. Attackers could exploit this race condition by carefully orchestrating concurrent operations that cause memory corruption during directory traversal operations. This type of vulnerability is particularly dangerous in kernel space because it operates at the most privileged level of the operating system, where successful exploitation can result in complete system compromise. The vulnerability affects systems using configfs filesystem and potentially other filesystem implementations that share similar locking patterns.
Mitigation strategies should focus on implementing proper synchronization mechanisms around directory traversal operations. The fix typically involves ensuring that proper locking is maintained throughout the entire duration of any directory traversal operation, rather than relying solely on parent directory locks. Organizations should prioritize applying the kernel patches provided by security vendors and monitor for related vulnerabilities in similar filesystem implementations. This vulnerability aligns with CWE-362 which describes race conditions in concurrent programming, and may map to ATT&CK techniques involving privilege escalation and system compromise through kernel-level exploits.
The fix implementation requires careful consideration of performance implications while maintaining security guarantees. Modern approaches often involve using read-write locks or other synchronization primitives that allow multiple readers but exclusive access for writers during critical sections of directory traversal operations. The vulnerability highlights the importance of thorough testing in concurrent environments and demonstrates why comprehensive security reviews of kernel code are essential for maintaining system integrity. System administrators should ensure their Linux kernels are updated to versions containing the appropriate patches, particularly in environments where configfs is actively used or where systems may be exposed to untrusted users or processes.