GNU LibreDWG Null Pointer Dereference Vulnerability in Dwggrep Utility

A null pointer dereference vulnerability has been identified in GNU LibreDWG versions through 0.14, specifically within the Dwggrep Utility. The issue arises in the match_BLOCK_HEADER function of dwggrep.c, where improper handling of certain input leads to a segmentation fault. This vulnerability requires local exploitation and has been publicly disclosed, with an associated proof-of-concept available.

Impact

Exploitation of this vulnerability causes a segmentation fault, leading to a crash of the LibreDWG application.

Reproduction

The vulnerability can be reproduced by processing a crafted DWG file with the Dwggrep utility. LibreDWG should be built with debugging information and AddressSanitizer enabled, using AFL++ as the fuzzer. After compiling the application, Dwggrep can be run with a regular expression that matches any content, which will trigger the null pointer dereference when the malformed DWG file is processed.