Micronaut has unbounded `formattersCache` in `TimeConverterRegistrar` that Allows Memory Exhaustion via `Accept-Language` Header — CVE-2026-44241

Summary

## Summary `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…

Product

maven: io.micronaut:micronaut-context

What to do

General, cautious steps (verify details in the official source):

• Prioritize patching or mitigation immediately (treat as actively risky).
• Identify affected product versions in your inventory and verify whether you are impacted.
• Apply vendor patches/updates or recommended mitigations as soon as available.
• Read the official advisory for exact affected versions and remediation steps.

Official advisory

• Read the official source
• CVE Record
• NVD

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