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.

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Advisories
Source ID Title
Github GHSA Github GHSA GHSA-8hjv-92q9-g4xj Micronaut has unbounded `formattersCache` in `TimeConverterRegistrar` that Allows Memory Exhaustion via `Accept-Language` Header
Fixes

Solution

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Workaround

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History

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'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

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

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

Link: CVE-2026-44241

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

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

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

Link: CVE-2026-44241

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-05-13T00:30:28Z

Weaknesses