Memory Allocation Vulnerability in Linux Kernel Affecting System Performance

CVE-2025-39756

What is CVE-2025-39756?

A vulnerability in the Linux kernel allows for excessive memory allocation when the file descriptor limit is set extremely high. This issue occurs because setting 'sysctl_nr_open' to a value like 1073741816 causes processes to attempt allocations that exceed the maximum integer size, resulting in impractical memory requests that may fail and trigger warnings. Specifically, when using functions like 'dup2' with high file descriptors, the kernel may attempt to allocate over 8 GB of memory, which can lead to performance degradation and system instability. A fix has been introduced to prevent such large allocation requests, ensuring smoother operation of the kernel.

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