Unauthenticated JVM crash via unbounded formatter cache
Published May 12, 2026 · Updated May 12, 2026
Resource exhaustion in Micronaut Core before 3.8.14, 3.10.0 through 3.10.5, and 4.3.0 through 4.10.21 allows remote attackers to crash the JVM. TimeConverterRegistrar concatenates each @Format pattern with the Accept-Language-derived locale and stores a DateTimeFormatter under that key in an unbounded ConcurrentHashMap. An exposed route with a @Format-annotated temporal parameter is required; novel BCP 47 private-use locale tags grow heap use until the server process terminates.
Summary
What happened
Resource exhaustion in Micronaut Core before 3.8.14, 3.10.0 through 3.10.5, and 4.3.0 through 4.10.21 allows remote attackers to crash the JVM. TimeConverterRegistrar concatenates each @Format pattern with the Accept-Language-derived locale and stores a DateTimeFormatter under that key in an unbounded ConcurrentHashMap. An exposed route with a @Format-annotated temporal parameter is required; novel BCP 47 private-use locale tags grow heap use until the server process terminates.
The record
- CVE
- CVE-2026-44241
- 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=>= 4.3.0, < 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
- GHSA-8hjv-92q9-g4xj denial-of-service proof of conceptproof of concept · unverified
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
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Your stack
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