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, 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.
History

Wed, 13 May 2026 16:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Wed, 13 May 2026 00:45:00 +0000

Type Values Removed Values Added
First Time appeared Micronaut-projects
Micronaut-projects micronaut-core
Vendors & Products Micronaut-projects
Micronaut-projects micronaut-core

Tue, 12 May 2026 22:00:00 +0000

Type Values Removed Values Added
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, 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.
Title Micronaut Framework: Unbounded formattersCache in TimeConverterRegistrar Allows Memory Exhaustion via Accept-Language Header
Weaknesses CWE-400
References
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}


cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published: 2026-05-12T21:20:45.249Z

Updated: 2026-05-13T15:37:00.461Z

Reserved: 2026-05-05T15:42:40.520Z

Link: CVE-2026-44241

cve-icon Vulnrichment

Updated: 2026-05-13T15:30:03.723Z

cve-icon NVD

Status : Deferred

Published: 2026-05-12T22:16:35.473

Modified: 2026-05-13T16:16:54.930

Link: CVE-2026-44241

cve-icon Redhat

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