CVE-2026-71267: microtar Stack Buffer Overflow in mtar_write_file_header() and mtar_write_dir_header()

microtar's mtarwritefileheader() and mtarwritedirheader() functions (src/microtar.c) copy a caller-supplied entry name into the 100-byte name field of a stack-allocated mtarheadert via strcpy(h.name, name), with no check that strlen(name) is less than 100 before the copy. Any application that calls these functions with an externally-influenced filename longer than 99 characters (e.g. when archiving user-supplied or attacker-controlled filenames) triggers a stack buffer overflow.