This program can segfault the parser by stackoverflow:

import ast

code = "f(" + ",".join(['a' for _ in range(100000)]) + ")"
print("Ready!")
ast.parse(code)

the reason is that the rule for arguments has a simple recursion when collecting args:

args[expr_ty]:
    [...]
    | a=named_expression b=[',' c=args { c }] {
        [...] }

Check https://github.com/we-like-parsers/pegen/issues/245 for more context and informaton