CVE-2022-1930: Regular expression denial of service in eth-account

The vulnerability stems from the TYPE_REGEX pattern in validation.py which was modified in the patch. The original regex had nested quantifiers that could cause catastrophic backtracking. The added test case demonstrates this by passing a 30-character '1' string that would cause >1 second delay with the old regex. While the exact function name isn't visible in diffs, the regex is clearly used in structured data validation flow called by encode_structured_data, as shown in the test's load_and_validate_structured_message call. The file path and regex usage context provide high confidence.