CVE-2025-21711: 
Linux Kernel vulnerability analysis and mitigation

CVE-2025-21711 affects the Linux kernel's ROSE socket implementation. The vulnerability was discovered in the rose_setsockopt() function where integer overflows could occur when handling unpredictably large arguments that are multiplied with other values. The issue was fixed in January 2025 with a patch that implements proper bounds checking (Kernel Commit).

The vulnerability exists in the net/rose/afrose.c file within the rosesetsockopt() function. The function previously used signed integers without proper bounds checking when multiplying user-supplied values with system constants (HZ). This could lead to integer overflows in various timer settings including T1, T2, T3, HOLDBACK, and IDLE timers. The fix involved changing the variable type from 'int' to 'unsigned int' and adding bounds checking using UINT_MAX/HZ comparisons (Kernel Commit).

If exploited, this vulnerability could lead to memory corruption due to integer overflow conditions when setting ROSE socket options. The issue affects systems using the ROSE (Radio Amateur AX.25) protocol implementation in the Linux kernel (CVE Details).

The issue has been fixed in the Linux kernel through a patch that implements proper bounds checking. System administrators should update to a kernel version that includes commit d640627663bfe7d8963c7615316d7d4ef60f3b0b. The fix changes the variable type to unsigned int and adds validation to prevent integer overflows (Kernel Commit).