What’s Vulnerable › Vulnerabilities

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

• Severity: low (CVSS 3.7 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-05-12 · updated 2026-10-26
• Weakness: CWE-400

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.

Affected products

• micronaut-projects micronaut-core: before 4.10.22

References

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

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