CVE-2026-63809

Name of the Vulnerable Software and Affected Versions Linux kernel versions prior to 7.1-rc5

Description Memory corruption can occur in the Linux kernel due to incorrect buffer deallocation. The proc sys call handler() function allocates a temporary sysctl buffer using kvzalloc(), which may use vmalloc() for large allocations. However, the buffer is subsequently freed using kfree(), which is inappropriate for vmalloc allocations and can lead to memory corruption or system crashes. This issue is triggered within the cgroup bpf run filter sysctl() function when handling sysctl write buffers.

Recommendations Replace the use of kfree() with kvfree() to safely handle both kmalloc and kvzalloc()/vmalloc() allocations in the proc sys call handler() function.