Description
Micronaut Framework is a JVM-based full stack Java framework designed for building modular, easily testable JVM applications. From 4.3.0 to before 4.10.22, 3.10.6, and 3.8.14, 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, 3.10.6, and 3.8.14.
References8
- github.com/micronaut-projects/micronaut-core/commit/48f05ae8dc4…
- github.com/micronaut-projects/micronaut-core/commit/c2048ab740c…
- github.com/micronaut-projects/micronaut-core/commit/c6ca8782de7…
- github.com/micronaut-projects/micronaut-core/releases/tag/v3.10…
- github.com/micronaut-projects/micronaut-core/releases/tag/v3.8.…
- github.com/micronaut-projects/micronaut-core/releases/tag/v4.10…
- github.com/micronaut-projects/micronaut-core/security/advisorie…
- github.com/micronaut-projects/micronaut-core/security/advisorie…
Metrics
- CVSS 3.1
-
7.5
HIGH
Score source: CNA
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - EPSS — exploit probability
- 1% percentile: 51 · as of 14 November 2026
- CWE
- CWE-400
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.