CVE-2026-44241

CVE-2026-44241 is a high-severity vulnerability with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-400.

Key facts

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.

Frequently asked questions

What is CVE-2026-44241?
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.
How severe is CVE-2026-44241?
CVE-2026-44241 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2026-44241 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (32nd percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2026-44241?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-44241 have an EU (EUVD) identifier?
Yes. CVE-2026-44241 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-29860.
When was CVE-2026-44241 published?
CVE-2026-44241 was published on 2026-05-12 and last updated on 2026-06-17.

References

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