CVE-2026-64010 in Linux
Summary
by MITRE • 07/19/2026
In the Linux kernel, the following vulnerability has been resolved:
nfc: llcp: Fix use-after-free race in nfc_llcp_recv_cc()
A race condition exists in the NFC LLCP connection state machine where the connection acceptance packet (CC) can be processed concurrently with socket release. This can lead to a use-after-free of the socket object.
When nfc_llcp_recv_cc() moves the socket from the connecting_sockets list to the sockets list, it does so without holding the socket lock. If llcp_sock_release() is executing concurrently, it might have already unlinked the socket and dropped its references, which can result in nfc_llcp_recv_cc() linking a freed socket into the live list.
Fix this by holding lock_sock() during the state transition and list movement in nfc_llcp_recv_cc(). After acquiring the lock, check if the socket is still hashed to ensure it hasn't already been unlinked and marked for destruction by the release path. This aligns the locking pattern with recv_hdlc() and recv_disc().
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Analysis
by VulDB Data Team • 07/19/2026
The vulnerability described represents a critical race condition in the Linux kernel's NFC LLCP (Link Layer Control Protocol) implementation that can lead to use-after-free conditions and potential system instability. This flaw exists within the nfc_llcp_recv_cc() function which handles connection acceptance packets in the NFC near field communication subsystem, specifically affecting the LLCP layer responsible for managing connections between NFC devices.
The technical root cause stems from improper locking mechanisms during socket state transitions within the NFC LLCP connection management code. When nfc_llcp_recv_cc() processes incoming connection acceptance packets, it performs a critical operation of moving socket objects from the connecting_sockets list to the active sockets list without acquiring the necessary socket lock protection. This unprotected state transition creates a window where concurrent execution paths can interfere with each other, particularly when llcp_sock_release() is simultaneously executing and attempting to clean up the same socket object.
The operational impact of this vulnerability extends beyond simple memory corruption to potentially enable privilege escalation or system crashes in environments utilizing NFC functionality. Attackers could exploit this race condition by carefully timing their actions to trigger concurrent execution of connection acceptance processing and socket release operations, leading to dereferencing of freed memory structures. Such exploitation could result in denial of service conditions, data corruption, or potentially more severe security implications depending on the execution context.
The fix implemented addresses this vulnerability through proper locking protocols that align with established kernel patterns used in similar functions like recv_hdlc() and recv_disc(). By incorporating lock_sock() during the state transition process, the implementation ensures atomicity of socket list modifications while preventing concurrent access from conflicting execution paths. The additional check for socket hash status after acquiring the lock serves as a crucial validation mechanism to confirm that the socket has not been unlinked and marked for destruction by the release path, thereby preventing the use-after-free scenario entirely.
This vulnerability classification aligns with CWE-367, which specifically addresses Time-of-Check to Time-of-Use (TOCTOU) race conditions, and demonstrates the importance of proper synchronization mechanisms in kernel space programming. The mitigation strategy follows established security practices from the ATT&CK framework's defense evasion categories, where improper locking can lead to memory corruption vulnerabilities that attackers might leverage for system compromise. The solution maintains consistency with kernel security best practices by ensuring that all socket list operations are properly synchronized and validated against concurrent modification scenarios that could otherwise lead to dangerous memory access patterns.
The resolution represents a fundamental improvement in kernel space concurrency control for NFC subsystem operations, addressing a class of vulnerabilities that commonly plague complex network protocol implementations where multiple execution paths must safely manipulate shared data structures. This fix reinforces the principle that critical data structure modifications in kernel code require proper locking mechanisms to prevent race conditions that could compromise system integrity and security posture across all NFC-enabled devices utilizing Linux kernel networking stacks.