GNU libredwg Layer Encoding dwg.spec DWG_TABLE null pointer dereference

A security flaw has been discovered in GNU libredwg 0.13.4. This impacts the function DWG_TABLE of the file src/dwg.spec of the component Layer Encoding. Performing a manipulation results in null pointer dereference. The attack needs to be approached locally. The exploit has been released to the public and may be used for attacks. Upgrading to version 0.14 will fix this issue. The patch is named f5b548c4c1697d66c3dabd0f6a49280a14365a3a. The affected component should be upgraded. The FIELD_HANDLE macro itself is NULL-safe (emits null_handle) - only the two raw zeroing assignments added by 27118c40 ("encode: also disable LAYER.material") dereferenced a NULL material handle; the fix restores the file's existing if (_obj->style) guard convention for material.