CVE-2025-0373

In order to export a file system via NFS, the file system must define a file system identifier (FID) for all exported files. Each FreeBSD file system implements operations to translate between FIDs and vnodes, the kernel's in-memory representation of files. These operations are VOP_VPTOFH(9) and VFS_FHTOVP(9). On 64-bit systems, the implementation of VOP_VPTOFH() in the cd9660, tarfs and ext2fs filesystems overflows the destination FID buffer by 4 bytes, a stack buffer overflow. A NFS server that exports a cd9660, tarfs, or ext2fs file system can be made to panic by mounting and accessing the export with an NFS client. Further exploitation (e.g., bypassing file permission checking or remote kernel code execution) is potentially possible, though this has not been demonstrated. In particular, release kernels are compiled with stack protection enabled, and some instances of the overflow are caught by this mechanism, causing a panic.