CVE-2024-53122 in Linux
Summary
by MITRE • 12/02/2024
In the Linux kernel, the following vulnerability has been resolved:
mptcp: cope racing subflow creation in mptcp_rcv_space_adjust
Additional active subflows - i.e. created by the in kernel path manager - are included into the subflow list before starting the 3whs.
A racing recvmsg() spooling data received on an already established subflow would unconditionally call tcp_cleanup_rbuf() on all the current subflows, potentially hitting a divide by zero error on the newly created ones.
Explicitly check that the subflow is in a suitable state before invoking tcp_cleanup_rbuf().
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Analysis
by VulDB Data Team • 02/14/2026
The vulnerability CVE-2024-53122 affects the Linux kernel's Multipath TCP implementation, specifically within the mptcp_rcv_space_adjust function. This issue stems from a race condition during subflow creation processes that can lead to critical system instability. The problem manifests when multiple subflows are created concurrently, with new subflows being added to the subflow list before the three-way handshake completion. This timing discrepancy creates a scenario where incoming data packets can be processed before the subflow is fully initialized, leading to potential system crashes or denial of service conditions.
The technical flaw occurs when a receiving message operation attempts to spool data on an already established subflow while new subflows are in the process of being created. The system unconditionally invokes tcp_cleanup_rbuf() on all current subflows without proper state validation, which can result in a divide by zero error when processing newly created subflows that haven't completed their initialization sequence. This condition represents a classic race condition vulnerability where concurrent operations interfere with each other's execution paths, violating the fundamental principles of thread safety and resource management in kernel space operations.
The operational impact of this vulnerability extends beyond simple system instability to potentially compromise network connectivity and service availability. When the divide by zero error occurs, it can cause kernel panics or system crashes that require manual intervention and system restarts. Network services relying on Multipath TCP functionality become vulnerable to denial of service attacks, as malicious actors could potentially trigger the race condition to disrupt network communications. The vulnerability affects systems using the kernel's built-in path manager for Multipath TCP operations, making it particularly concerning for high-availability network infrastructure and servers handling multiple concurrent connections.
The fix implemented addresses the race condition by adding explicit state validation before calling tcp_cleanup_rbuf(). This mitigation follows established security practices for preventing race conditions in kernel-level code, aligning with CWE-362 which catalogs concurrency issues and CWE-367 which addresses time-of-check to time-of-use vulnerabilities. The solution ensures that subflows are in a suitable operational state before resource cleanup operations are performed, preventing the divide by zero error that could occur when processing uninitialized subflows. This approach also aligns with ATT&CK technique T1499.004 for network disruption and T1566.001 for malicious code execution through system vulnerabilities, as the fix prevents both system instability and potential exploitation scenarios. Organizations should prioritize applying this kernel update to maintain network stability and prevent potential exploitation of the race condition by attackers seeking to disrupt network services through carefully crafted packet sequences.