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GHSA-43w5-mmxv-cpvh

HighCVSS 8.2 / 10
Published Mar 17, 2026·Last modified Mar 31, 2026
Affected Components(0)

No affected components available

Description

In JsonBeanPropertyBinder::expandArrayToThreshold in io.micronaut:micronaut-json-core before Micronaut 4 4.10.16 and in Micronaut 3 before 3.10.5 does not correctly handle descending array index order during form-urlencoded body binding, which allows remote attackers to cause a denial of service (non-terminating loop, CPU exhaustion, and OutOfMemoryError) via crafted indexed form parameters (e.g., authors[1].name followed by authors[0].name).

Example

With such an application

package dosform;

import io.micronaut.http.HttpResponse;
import io.micronaut.http.MediaType;
import io.micronaut.http.annotation.Body;
import io.micronaut.http.annotation.Consumes;
import io.micronaut.http.annotation.Controller;
import io.micronaut.http.annotation.Get;
import io.micronaut.http.annotation.Post;
import io.micronaut.http.annotation.Produces;

import java.net.URI;

@Controller
class HomeController {

    @Produces(MediaType.TEXT_HTML)
    @Get
    String index() {
        return """
                <!DOCTYPE html>
                <html>
                <head>
                <title></title>
                </head>
                <body>
    <form action="/submit" method="post">
      <label for="firstAuthor">Fist Author</label>
      <input id="firstAuthor" name="authors[0].name" type="text"/>

      <label for="secondAuthor">Second Author</label>
      <input id="secondAuthor" name="authors[1].name" type="text"/>
      
      <label for="thirdAuthor">Third Author</label>
      <input id="thirdAuthor" name="authors[2].name" type="text"/>

      <button type="submit">Submit</button>
    </form>
               
                </body>
                </html>
                """;
    }

    @Consumes(MediaType.APPLICATION_FORM_URLENCODED)
    @Post("/submit")
    HttpResponse<?> submit(@Body Book book) {
        return HttpResponse.seeOther(URI.create("/"));
    }
}
package dosform;

import io.micronaut.core.annotation.Introspected;

import java.util.Objects;

@Introspected
public class Author {
    private String name;
    public String getName() { return name; }
    public void setName(String name) { this.name = name; }

    @Override
    public final boolean equals(Object o) {
        if (!(o instanceof Author)) return false;

        Author author = (Author) o;
        return Objects.equals(name, author.name);
    }

    @Override
    public int hashCode() {
        return Objects.hashCode(name);
    }

    @Override
    public String toString() {
        return "Author{" +
                "name='" + name + '\'' +
                '}';
    }
}
package dosform;

import io.micronaut.core.annotation.Introspected;

import java.util.List;
import java.util.Objects;

@Introspected
public class Book {
    private List<Author> authors;
    public List<Author> getAuthors() { return authors; }
    public void setAuthors(List<Author> authors) { this.authors = authors; }

    @Override
    public final boolean equals(Object o) {
        if (!(o instanceof Book)) return false;

        Book book = (Book) o;
        return Objects.equals(authors, book.authors);
    }

    @Override
    public int hashCode() {
        return Objects.hashCode(authors);
    }

    @Override
    public String toString() {
        return "Book{" +
                "authors=" + authors +
                '}';
    }
}

Sending curl -v -X POST 'http://127.0.0.1:8080/submit' -H 'Content-Type: application/x-www-form-urlencoded' --data-urlencode 'authors[1].name=RobertGalbraith' --data-urlencode 'authors[0].name=JKRowling' causes sustained CPU usage and unbounded memory growth (eventually OutOfMemoryError).

Patches

For Micronaut 4, the problem has been patched in micronaut-core, dependencies with group id io.micronaut, since 4.10.16.

For Micronaut 3, the problem has been patched since 3.10.5

Users upgrade to the latest version of the framework.

Workarounds

There is no way for users to fix or remediate the vulnerability without upgrading.

References

PR Fix: https://github.com/micronaut-projects/micronaut-core/pull/12410

Risk Scores
Base Score
8.2

The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker does not need any special privileges or access rights. No user interaction is needed for the attacker to exploit this vulnerability.

Threat Intelligence
4.6

Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.

EPSS
0.60%

The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.

Exploit
Not available

We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.

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