PYSEC-2026-3832 eml_parser vulnerable to DoS via deeply nested parens in Received headers

Summary emlparser strips parenthesised CFWS comments from Received: headers using a regex-based fix-point loop. The loop has quadratic time complexity in the number of nested parens. A single Received: header containing 5,000 nested parens causes 1.3 seconds of CPU saturation per parsed message;...