Heap/stack buffer overflow in the dlang_lname function in d-demangle.c in libiberty allows attackers to potentially cause a denial of service (segmentation fault and crash) via a crafted mangled symbol.
https://gcc.gnu.org/pipermail/gcc-patches/2021-September/579987
https://gcc.gnu.org/git/?p=gcc.git%3Ba=commit%3Bh=5481040197402be6dfee265bd2ff5a4c88e30505