CVE-2026-33013: Micronaut vulnerable to DoS via crafted form-urlencoded body binding with descending array indices

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.6% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-03-20 · updated 2026-06-17
Weakness: CWE-835

Description

Micronaut Framework is a JVM-based full stack Java framework designed for building modular, easily testable JVM applications. Versions prior to both 4.10.16 and 3.10.5 do not correctly handle descending array index order during form-urlencoded body binding in theJsonBeanPropertyBinder::expandArrayToThreshold, which allows remote attackers to cause a DoS (non-terminating loop, CPU exhaustion, and OutOfMemoryError) via crafted indexed form parameters (e.g., authors[1].name followed by authors[0].name). This issue has been fixed in versions 4.10.16 and 3.10.5.

Affected products

micronaut-projects micronaut-core: before 3.10.5; from 4.0.0 before 4.10.16 — fixed in 3.10.5, 4.10.16

How to fix

Upgrade to a fixed version: micronaut-projects micronaut-core 3.10.5, 4.10.16. Check the vendor advisory for mitigations.

References

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