https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110862
Bug ID: 110862 Summary: format out of bands read on format string "{0:{0}" Product: gcc Version: 13.2.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: libstdc++ Assignee: unassigned at gcc dot gnu.org Reporter: gcc at pauldreik dot se Target Milestone: --- The following program with an incorrect format string causes an out of bounds read when compiled with gcc 13.2: #include <cstdio> #include <format> int main() { unsigned short v = 0; std::puts(std::vformat("{0:{0}", std::make_format_args(v)).c_str()); } I expected an exception to be thrown. Link to reproducer: https://godbolt.org/z/WrqxGE1jG