Uncontrolled Resource Consumption

Summary

Micronaut Framework is a JVM-based full stack Java framework designed for building modular, easily testable JVM applications. In versions 4.3.0 prior to 4.10.22 and 5.x prior to 5.0.0-M25, `TimeConverterRegistrar` caches `DateTimeFormatter` instances in an unbounded `ConcurrentHashMap<String, DateTimeFormatter>` whose key is derived from the `@Format` annotation pattern concatenated with the locale from the HTTP Accept-Language header. Because `Locale.forLanguageTag()` accepts arbitrary BCP 47 private-use extensions (en-x-a001, en-x-a002, ...), an unauthenticated attacker can generate an unlimited number of unique cache keys by sending requests with novel locale tags, growing the cache until heap memory is exhausted and the JVM crashes. This vulnerability is fixed in 4.10.22 and 5.0.0-M25.