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Low, CVSS 3.7

Micronaut has Unbounded bundleCache in ResourceBundleMessageSource that Allows Memory Exhaustion via Accept-Language Header

CVE-2026-44242GHSA-3rfq-4wpf-qqw3

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (io.micronaut:micronaut-inject 4.10.22, 3.10.6, 3.8.14), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
3.7 · CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L
EPSS
  • CVE-2026-44242: 0.26% estimated exploitation activity in the next 30 days; percentile 17.12 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

Summary ResourceBundleMessageSource maintains two caches: messageCache (bounded at 100 entries via ConcurrentLinkedHashMap) and bundleCache (unbounded ConcurrentHashMap). 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. Unlike GHSA-2hcp-gjrf-7fhc and the sibling messageCache (both bounded), bundleCache was not updated to use a bounded cache implementation. Details The bundleCache is initialized in inject/src/main/java/io/micronaut/context/i18n/ResourceBundleMessageSource.java at line 150: The resolveBundle() method at line 169 inserts into bundleCache with no eviction policy: The attack path requires: 1. The application registers a…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 1 · created ·

    Published from ghsa record GHSA-3rfq-4wpf-qqw3

Agent brief

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# Patch Next advisory brief: CVE-2026-44242

Advisory: Micronaut has Unbounded `bundleCache` in `ResourceBundleMessageSource` that Allows Memory Exhaustion via `Accept-Language` Header
IDs: CVE-2026-44242, GHSA-3rfq-4wpf-qqw3
Record: https://patchnext.com/advisories/cve-2026-44242 (revision 1, source checked 26 Oct 2026, 16:54 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Low (CVSS 3.7)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: io.micronaut:micronaut-inject 4.10.22, 3.10.6, 3.8.14. A vendor fix does not mean a deployment is fixed.

## Affected components
- Maven io.micronaut:micronaut-inject: affected >= 4.10.0, < 4.10.22; >= 3.10.0, < 3.10.6; < 3.8.14; fixed in 3.8.14, 4.10.22, 3.10.6

## Suggested inspection (read-only)
- Maven io.micronaut:micronaut-inject: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on io.micronaut:micronaut-inject.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-3rfq-4wpf-qqw3 (GitHub-reviewed advisory GHSA-3rfq-4wpf-qqw3 lists affected ranges: Maven io.micronaut:micronaut-inject >=4.10.0 =3.10.0 =0 <3.8.14)

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