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

CVE-2026-44241 + Micronaut has unbounded formattersCache in TimeConverterRegistrar that Allows Memory Exhaustion via Accept-Language Head + High + 2026-05-06

One-sentence business risk

Broken authentication or authorization can expose tenant data and administrator actions, which buyers treat as a release blocker.

Research notes

  • Root cause: ## 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 head.
  • Affected versions: maven:io.micronaut:micronaut-context >= 4.3.0, < 4.10.22; maven:io.micronaut:micronaut-context >= 3.10.0, < 3.10.6; maven:io.micronaut:micronaut-context < 3.8.14.
  • Fixed / safe versions: 3.10.6, 3.8.14, 4.10.22.
  • Public exploit / PoC signal: the consulted NVD/GHSA/vendor sources describe the trigger class; treat it as reproducible until patched.
  • CVSS: use upstream advisory score .

Exact vulnerable code pattern

update_or_read(request.body.target_id)  # no owner/role check

Fixed / mitigated code pattern

target = load_owned_resource(actor, target_id); require_role(actor, target, "admin")

Dependency or runtime update:

mvn -q dependency:tree | grep -i micronaut-context || true
# update Maven/Gradle coordinates to 3.10.6, 3.8.14, 4.10.22

Step-by-step integration guide

  1. Inventory io.micronaut:micronaut-context across source, lockfiles, SBOMs, container images, CI images, and deployment manifests.
  2. Upgrade to 3.10.6, 3.8.14, 4.10.22 or apply the exact vendor patch referenced below.
  3. Replace the vulnerable authz pattern with the fixed pattern and fail closed on malformed input.
  4. Add a regression test that exercises the advisory trigger and proves the request is rejected, bounded, or authorized.
  5. Deploy through canary, monitor security logs and resource metrics, then remove temporary edge blocks only after all runtimes are fixed.

Alternative mitigations

  • Disable the vulnerable feature path while the package/runtime update rolls out.
  • Add WAF or reverse-proxy rules for traversal tokens, prototype-polluting keys, oversized frames, shell metacharacters, or unauthenticated tool calls matching the trigger class.
  • Restrict internal egress, rotate exposed secrets, and revoke affected tokens/keys if the vulnerability can disclose config, logs, JWT secrets, proxy credentials, or PKI material.
  • For admin/API authorization issues, temporarily require elevated roles and explicit ownership checks at the gateway.

Detection signature

id: cve-2026-44241-micronaut-has-unbounded-formatterscache-in-timec
source: "GitHub Advisory Database"
dependency_or_product: "io.micronaut:micronaut-context"
affected: "maven:io.micronaut:micronaut-context >= 4.3.0, < 4.10.22; maven:io.micronaut:micronaut-context >= 3.10.0, < 3.10.6; maven:io.micronaut:micronaut-context < 3.8.14"
fixed: "3.10.6, 3.8.14, 4.10.22"
signals:
  - "authz"
  - "../"
  - "__proto__"
  - "tools/call"
  - "wp_ajax_nopriv"
  - "pickle.loads"
  - "shell command construction"
action: "upgrade, add regression test, and verify deploy artifact"

Copy-paste skill

You are remediating CVE-2026-44241 (Micronaut has unbounded formattersCache in TimeConverterRegistrar that Allows Memory Exhaustion via Accept-Language Head) in this repository.

Find every affected dependency, runtime, image, service configuration, and reachable code path. Upgrade or patch to 3.10.6, 3.8.14, 4.10.22. Replace the vulnerable authz pattern with a fail-closed implementation, add a regression test for the trigger shape, and update deployment/SBOM artifacts. If this repository does not control the affected runtime, create TRIAGE.md naming the owner, affected version, fixed version, and blocking decision.

Keywords, affected tech stack, and revenue tags

  • Keywords: CVE-2026-44241, authz, io.micronaut:micronaut-context, GitHub Advisory Database.
  • Affected tech stack: java/maven.
  • Revenue tags: sellable_to_fintech, enterprise_blocker, high_priority_sla.

References