CVE-2026-33013: Micronaut json core Denial of Service Vulnerability

HIGH
Advisory Identifier: GHSA-43w5-mmxv-cpvh
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CWE-835
Published
Advisory Summary

CVE-2026-33013 is a HIGH denial of service vulnerability (CWE-835: Loop with Unreachable Exit Condition ('Infinite Loop')) affecting Micronaut json core libraries in the Maven ecosystem. The issue involves micronaut vulnerable to dos via crafted form-urlencoded body binding with descending array indices. Remediation is available by upgrading affected packages to version 4.10.16, 3.10.5, 3.8.13.

CVE-2026-33013 at a Glance

CVE Identifier CVE-2026-33013
GHSA Identifier GHSA-43w5-mmxv-cpvh
Severity HIGH
CVSS v3.1 Base Score N/A
CWE Classification CWE-835: Loop with Unreachable Exit Condition ('Infinite Loop')
Affected Product Micronaut json core
Package Ecosystem Maven
Published Date
Last Updated

How to Fix CVE-2026-33013

To remediate this vulnerability, upgrade all affected Micronaut json core dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

io.micronaut:micronaut-json-core fixed: 4.10.16 
<dependency>
    <groupId>io.micronaut</groupId>
    <artifactId>micronaut-json-core</artifactId>
    <version>4.10.16</version>
</dependency>
io.micronaut:micronaut-json-core fixed: 3.10.5 
<dependency>
    <groupId>io.micronaut</groupId>
    <artifactId>micronaut-json-core</artifactId>
    <version>3.10.5</version>
</dependency>
io.micronaut:micronaut-json-core fixed: 3.8.13 
<dependency>
    <groupId>io.micronaut</groupId>
    <artifactId>micronaut-json-core</artifactId>
    <version>3.8.13</version>
</dependency>
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

mvn dependency:tree -Dincludes=io.micronaut

How to Check if You Are Affected

To determine whether your Java application is affected by CVE-2026-33013, inspect your build dependencies using the Maven Dependency Plugin:

mvn dependency:tree -Dincludes=io.micronaut

Analyze the terminal output to locate any version of Micronaut json core in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 4.10.16), your application is affected.

Note: The mvn dependency:tree -Dincludes=io.micronaut command inspects the resolved dependency graph declared in your project's POM files; it does not perform automated security scanning or inspect runtime dynamic classpaths. Always verify runtime container classpaths and shaded JARs.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-835: Loop with Unreachable Exit Condition ('Infinite Loop'), where the product contains an iteration or loop with an exit condition that cannot be reached, i.e., an infinite loop. In Micronaut json core, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

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 ```java 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](https://github.com/micronaut-projects/micronaut-core/releases/tag/v4.10.16). For Micronaut 3, the problem has been patched since [3.10.5](https://github.com/micronaut-projects/micronaut-core/releases/tag/v3.10.5) 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

CVE-2026-33013 Affected Micronaut json core Versions

3 component(s)
Fixed Versions:
4.10.163.10.53.8.13
Product / Package Ecosystem Affected Versions Fixed Version
io.micronaut:micronaut-json-core
maven/io.micronaut/micronaut-json-core
Maven
≥ 4.0.0-M1
< 4.10.16
4.10.16
io.micronaut:micronaut-json-core
maven/io.micronaut/micronaut-json-core
Maven
≥ 3.9.0
< 3.10.5
3.10.5
io.micronaut:micronaut-json-core
maven/io.micronaut/micronaut-json-core
Maven
< 3.8.13
3.8.13

References

GitHub Advisory / Wiki ADVISORY
https://github.com/micronaut-projects/micronaut-core/security/advisories/GHSA-43w5-mmxv-cpvh
NVD — CVE-2026-33013 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-33013
Micronaut json core Source Repository REPOSITORY
https://github.com/micronaut-projects/micronaut-core/pull/12410
Security Fix Commit FIX COMMIT
https://github.com/micronaut-projects/micronaut-core/commit/1afe509677c51b320041b7a2c177366d4a4deb55
Micronaut json core Source Repository REPOSITORY
https://github.com/micronaut-projects/micronaut-core
Micronaut json core Release RELEASE
https://github.com/micronaut-projects/micronaut-core/releases/tag/v3.10.5
Micronaut json core Release RELEASE
https://github.com/micronaut-projects/micronaut-core/releases/tag/v4.10.16

Frequently Asked Questions

What is CVE-2026-33013?
CVE-2026-33013 is a security vulnerability in Micronaut json core involving Micronaut vulnerable to DoS via crafted form-urlencoded body binding with descending array indices under CWE-835: Loop with Unreachable Exit Condition ('Infinite Loop').
Which Micronaut json core versions are affected?
Affected versions include releases prior to 4.10.16, 3.10.5, 3.8.13 across affected packages: io.micronaut:micronaut-json-core.
What version fixes CVE-2026-33013?
Upgrading to 4.10.16, 3.10.5, 3.8.13 (or the latest patched release for your respective branch) resolves the vulnerability.
Is micronaut-json-core affected?
Yes, io.micronaut:micronaut-json-core is affected in releases prior to 4.10.16, 3.10.5, 3.8.13. Upgrade your dependency to 4.10.16, 3.10.5, 3.8.13 or later.
What CWE is associated with CVE-2026-33013?
CVE-2026-33013 is classified under CWE-835: Loop with Unreachable Exit Condition ('Infinite Loop') (The product contains an iteration or loop with an exit condition that cannot be reached, i.e., an infinite loop.).
How can I check Maven dependencies for CVE-2026-33013?
Run the dependency tree command: 'mvn dependency:tree -Dincludes=io.micronaut'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-43w5-mmxv-cpvh",
  "modified" : "2026-03-31T18:45:02Z",
  "published" : "2026-03-17T16:59:59Z",
  "aliases" : [ "CVE-2026-33013" ],
  "summary" : "Micronaut vulnerable to DoS via crafted form-urlencoded body binding with descending array indices",
  "details" : "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`).\n\n### Example\n\nWith such an application\n\n```java\npackage dosform;\n\nimport io.micronaut.http.HttpResponse;\nimport io.micronaut.http.MediaType;\nimport io.micronaut.http.annotation.Body;\nimport io.micronaut.http.annotation.Consumes;\nimport io.micronaut.http.annotation.Controller;\nimport io.micronaut.http.annotation.Get;\nimport io.micronaut.http.annotation.Post;\nimport io.micronaut.http.annotation.Produces;\n\nimport java.net.URI;\n\n@Controller\nclass HomeController {\n\n    @Produces(MediaType.TEXT_HTML)\n    @Get\n    String index() {\n        return \"\"\"\n                <!DOCTYPE html>\n                <html>\n                <head>\n                <title></title>\n                </head>\n                <body>\n    <form action=\"/submit\" method=\"post\">\n      <label for=\"firstAuthor\">Fist Author</label>\n      <input id=\"firstAuthor\" name=\"authors[0].name\" type=\"text\"/>\n\n      <label for=\"secondAuthor\">Second Author</label>\n      <input id=\"secondAuthor\" name=\"authors[1].name\" type=\"text\"/>\n      \n      <label for=\"thirdAuthor\">Third Author</label>\n      <input id=\"thirdAuthor\" name=\"authors[2].name\" type=\"text\"/>\n\n      <button type=\"submit\">Submit</button>\n    </form>\n               \n                </body>\n                </html>\n                \"\"\";\n    }\n\n    @Consumes(MediaType.APPLICATION_FORM_URLENCODED)\n    @Post(\"/submit\")\n    HttpResponse<?> submit(@Body Book book) {\n        return HttpResponse.seeOther(URI.create(\"/\"));\n    }\n}\npackage dosform;\n\nimport io.micronaut.core.annotation.Introspected;\n\nimport java.util.Objects;\n\n@Introspected\npublic class Author {\n    private String name;\n    public String getName() { return name; }\n    public void setName(String name) { this.name = name; }\n\n    @Override\n    public final boolean equals(Object o) {\n        if (!(o instanceof Author)) return false;\n\n        Author author = (Author) o;\n        return Objects.equals(name, author.name);\n    }\n\n    @Override\n    public int hashCode() {\n        return Objects.hashCode(name);\n    }\n\n    @Override\n    public String toString() {\n        return \"Author{\" +\n                \"name='\" + name + '\\'' +\n                '}';\n    }\n}\npackage dosform;\n\nimport io.micronaut.core.annotation.Introspected;\n\nimport java.util.List;\nimport java.util.Objects;\n\n@Introspected\npublic class Book {\n    private List<Author> authors;\n    public List<Author> getAuthors() { return authors; }\n    public void setAuthors(List<Author> authors) { this.authors = authors; }\n\n    @Override\n    public final boolean equals(Object o) {\n        if (!(o instanceof Book)) return false;\n\n        Book book = (Book) o;\n        return Objects.equals(authors, book.authors);\n    }\n\n    @Override\n    public int hashCode() {\n        return Objects.hashCode(authors);\n    }\n\n    @Override\n    public String toString() {\n        return \"Book{\" +\n                \"authors=\" + authors +\n                '}';\n    }\n}\n```\n\nSending `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`). \n\n### Patches\nFor Micronaut 4, the problem has been patched in `micronaut-core`, dependencies with group id `io.micronaut`, since [4.10.16](https://github.com/micronaut-projects/micronaut-core/releases/tag/v4.10.16).\n\nFor Micronaut 3, the problem has been patched since [3.10.5](https://github.com/micronaut-projects/micronaut-core/releases/tag/v3.10.5)\n\nUsers upgrade to the latest version of the framework. \n\n### Workarounds\nThere is no way for users to fix or remediate the vulnerability without upgrading.\n\n### References\nPR Fix: https://github.com/micronaut-projects/micronaut-core/pull/12410",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "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"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Maven",
      "name" : "io.micronaut:micronaut-json-core"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "4.0.0-M1"
      }, {
        "fixed" : "4.10.16"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Maven",
      "name" : "io.micronaut:micronaut-json-core"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "3.9.0"
      }, {
        "fixed" : "3.10.5"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Maven",
      "name" : "io.micronaut:micronaut-json-core"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "3.8.13"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/micronaut-projects/micronaut-core/security/advisories/GHSA-43w5-mmxv-cpvh"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-33013"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/micronaut-projects/micronaut-core/pull/12410"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/micronaut-projects/micronaut-core/commit/1afe509677c51b320041b7a2c177366d4a4deb55"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/micronaut-projects/micronaut-core"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/micronaut-projects/micronaut-core/releases/tag/v3.10.5"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/micronaut-projects/micronaut-core/releases/tag/v4.10.16"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-835" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-03-17T16:59:59Z",
    "nvd_published_at" : "2026-03-20T05:16:15Z"
  }
}