HTTP::Date versions before 6.08 for Perl allow CPU exhaustion via polynomial regex backtracking in parse_date. parse_date() matches the date string against a chain of alternative regexes, and str2ti…

Summary

HTTP::Date versions before 6.08 for Perl allow CPU exhaustion via polynomial regex backtracking in parse_date. parse_date() matches the date string against a chain of alternative regexes, and str2time() delegates to it. Several of these patterns place unbounded quantifiers next to each other before a trailing `\s*$` anchor. A valid date prefix followed by a long interior run of digits, letters, or whitespace and a single trailing byte that defeats the final match forces the engine to repartiti…