Heap exhaustion via unbounded locale bundle cache
Published May 12, 2026 · Updated May 12, 2026
Uncontrolled resource consumption in Micronaut Core allows remote attackers to exhaust application heap memory through HTTP requests. The ResourceBundleMessageSource.resolveBundle method stores every attacker-controlled Accept-Language locale and base-name pair in bundleCache without a size limit or eviction. Exploitation requires an explicitly registered ResourceBundleMessageSource bean, HTML error responses, and sustained requests; heap exhaustion interrupts the service.
Summary
What happened
Uncontrolled resource consumption in Micronaut Core allows remote attackers to exhaust application heap memory through HTTP requests. The ResourceBundleMessageSource.resolveBundle method stores every attacker-controlled Accept-Language locale and base-name pair in bundleCache without a size limit or eviction. Exploitation requires an explicitly registered ResourceBundleMessageSource bean, HTML error responses, and sustained requests; heap exhaustion interrupts the service.
The record
- CVE
- CVE-2026-44242
- Published
- May 12, 2026
- Updated
- May 12, 2026
- Vendor
- Micronaut Foundation
- Product
- Micronaut Core
- Classifications
- CWE-400, T1499.003
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- May 12, 2026CVE publishedPublication date reported by the CVE source.
- May 12, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=< 4.10.22
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- Upstream Accept-Language cache-exhaustion proof of conceptproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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