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

> Remote attackers can cause denial of service via CPU exhaustion and memory errors by sending crafted form-urlencoded data with descending array indices.

- **Severity:** High 8.2 (`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`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 20 Mar 2026
- **Updated:** 25 Mar 2026
- **Also known as:** CLEANSTART-2026-OE40896, CLSA-2026-1787664048, CLSA-2026-1788443284, GHSA-43w5-mmxv-cpvh, MINI-gx69-56rx-7wg6

## What is CVE-2026-33013?

CVE-2026-33013 is a high-severity denial of service vulnerability in micronaut-projects micronaut-core, published on 20 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official 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.

Weakness: CWE-835 (Loop with Unreachable Exit Condition)

## Which versions are affected by CVE-2026-33013?

6 open source packages ship an affected version, including io.micronaut:micronaut-json-core. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `io.micronaut:micronaut-json-core` | Maven | All versions | 3.8.13 |
| `io.micronaut:micronaut-json-core` | Maven | All versions | 3.8.13 |
| `io.micronaut:micronaut-json-core` | Maven | From 3.9.0 | 3.10.5 |
| `io.micronaut:micronaut-json-core` | Maven | From 3.9.0 | 3.10.5 |
| `io.micronaut:micronaut-json-core` | Maven | From 4.0.0-M1 | 4.10.16 |
| `io.micronaut:micronaut-json-core` | Maven | From 4.0.0-M1 | 4.10.16 |

Products: Objectcomputing Micronaut.

## How do I fix CVE-2026-33013?

Upgrade io.micronaut:micronaut-json-core to a fixed version for your release line: 3.8.13, 3.10.5 or 4.10.16.

## Is CVE-2026-33013 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-33013 exists.

## Other vulnerabilities in micronaut-projects micronaut-core

- [CVE-2020-7611](https://insights.sbomify.com/CVE-2020-7611/): Micronaut's HTTP client is vulnerable to HTTP Request Header Injection (critical 9.8)
- [CVE-2026-33012](https://insights.sbomify.com/CVE-2026-33012/): Micronaut Framework vulnerable to a Denial of Service in HTML error response caching (high 7.5)
- [CVE-2021-32769](https://insights.sbomify.com/CVE-2021-32769/): Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') in micronaut-core (high 7.5)
- [CVE-2022-21700](https://insights.sbomify.com/CVE-2022-21700/): Memory leak in micronaut-core (medium 5.3)
- [CVE-2024-23639](https://insights.sbomify.com/CVE-2024-23639/): micronaut-core management endpoints vulnerable to drive-by localhost attack (medium 5.1)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-33013 and fix it if it is affected.

What it is: CVE-2026-33013 is a high-severity denial of service vulnerability in micronaut-projects micronaut-core, published on 20 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-33013 exists.

Affected packages and fixed versions:
- io.micronaut:micronaut-json-core (Maven): affected all versions; fixed in 3.8.13
- io.micronaut:micronaut-json-core (Maven): affected all versions; fixed in 3.8.13
- io.micronaut:micronaut-json-core (Maven): affected from 3.9.0; fixed in 3.10.5
- io.micronaut:micronaut-json-core (Maven): affected from 3.9.0; fixed in 3.10.5
- io.micronaut:micronaut-json-core (Maven): affected from 4.0.0-M1; fixed in 4.10.16
- io.micronaut:micronaut-json-core (Maven): affected from 4.0.0-M1; fixed in 4.10.16

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-33013/ (Markdown: https://insights.sbomify.com/CVE-2026-33013/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-33013
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-33013
- OSV: https://osv.dev/vulnerability/CVE-2026-33013

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-33013/
Summaries are generated and may contain mistakes; the official description above is the record.