CVE-2026-3260: Undertow Denial of Service Vulnerability

MODERATE
Advisory Identifier: GHSA-3x3v-w654-m28m
Share
CVSS 5.9
CWE-770
Published
Advisory Summary

CVE-2026-3260 is a MODERATE (CVSS 5.9) denial of service vulnerability (CWE-770: Allocation of Resources Without Limits or Throttling) affecting Undertow libraries in the Maven ecosystem. The issue involves denial of service via multipart/form-data parsing on http get requests. Remediation is available in the latest vendor maintenance releases.

CVE-2026-3260 at a Glance

CVE Identifier CVE-2026-3260
GHSA Identifier GHSA-3x3v-w654-m28m
Severity MODERATE
CVSS v3.1 Base Score 5.9
CWE Classification CWE-770: Allocation of Resources Without Limits or Throttling
Affected Product Undertow
Package Ecosystem Maven
Published Date
Last Updated

Security Impact

CVSS: 5.9

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H).

Attack Vector Network (AV:N)
Attack Complexity High (AC:H)
Privileges Required None (PR:N)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality None (C:N)
Integrity None (I:N)
Availability High (A:H)

How to Fix CVE-2026-3260

To remediate this vulnerability, upgrade all affected Undertow 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.undertow:undertow-core fixed: Latest secure release 
<dependency>
    <groupId>io.undertow</groupId>
    <artifactId>undertow-core</artifactId>
    <version>Latest secure release</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.undertow

How to Check if You Are Affected

To determine whether your Java application is affected by CVE-2026-3260, inspect your build dependencies using the Maven Dependency Plugin:

mvn dependency:tree -Dincludes=io.undertow

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

Note: The mvn dependency:tree -Dincludes=io.undertow 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-770: Allocation of Resources Without Limits or Throttling, where the product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated. In Undertow, 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

A flaw was found in Undertow. A remote attacker could exploit this vulnerability by sending an HTTP GET request containing multipart/form-data content. If the underlying application processes parameters using methods like `getParameterMap()`, the server prematurely parses and stores this content to disk. This could lead to resource exhaustion, potentially resulting in a Denial of Service (DoS).

CVE-2026-3260 Affected Undertow Versions

1 component(s)
Product / Package Ecosystem Affected Versions Fixed Version
io.undertow:undertow-core
maven/io.undertow/undertow-core
Maven

References

NVD — CVE-2026-3260 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-3260
Undertow Security Information SECURITY
https://access.redhat.com/security/cve/CVE-2026-3260
bugzilla.redhat.com/show_bug.cgi WEB
https://bugzilla.redhat.com/show_bug.cgi?id=2443010
Undertow Source Repository REPOSITORY
https://github.com/undertow-io/undertow

Frequently Asked Questions

What is CVE-2026-3260?
CVE-2026-3260 is a security vulnerability in Undertow involving Denial of Service via Multipart/Form-Data Parsing on HTTP GET Requests under CWE-770: Allocation of Resources Without Limits or Throttling.
Which Undertow versions are affected?
Affected versions include releases prior to current release patches across affected packages: io.undertow:undertow-core.
What version fixes CVE-2026-3260?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
Is undertow-core affected?
Yes, io.undertow:undertow-core is affected in releases prior to Latest secure release. Upgrade your dependency to Latest secure release or later.
What is the CVSS score of CVE-2026-3260?
CVE-2026-3260 has a CVSS v3.1 base score of 5.9 (MODERATE) with vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H.
What CWE is associated with CVE-2026-3260?
CVE-2026-3260 is classified under CWE-770: Allocation of Resources Without Limits or Throttling (The product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated.).
How can I check Maven dependencies for CVE-2026-3260?
Run the dependency tree command: 'mvn dependency:tree -Dincludes=io.undertow'. 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-3x3v-w654-m28m",
  "modified" : "2026-06-30T21:23:42Z",
  "published" : "2026-03-24T06:31:13Z",
  "aliases" : [ "CVE-2026-3260" ],
  "summary" : "Undertow: Denial of Service via Multipart/Form-Data Parsing on HTTP GET Requests",
  "details" : "A flaw was found in Undertow. A remote attacker could exploit this vulnerability by sending an HTTP GET request containing multipart/form-data content. If the underlying application processes parameters using methods like `getParameterMap()`, the server prematurely parses and stores this content to disk. This could lead to resource exhaustion, potentially resulting in a Denial of Service (DoS).",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Maven",
      "name" : "io.undertow:undertow-core"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "< 2.4.0.Beta1"
    }
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-3260"
  }, {
    "type" : "WEB",
    "url" : "https://access.redhat.com/security/cve/CVE-2026-3260"
  }, {
    "type" : "WEB",
    "url" : "https://bugzilla.redhat.com/show_bug.cgi?id=2443010"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/undertow-io/undertow"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-770" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-03-27T20:45:48Z",
    "nvd_published_at" : "2026-03-24T05:16:24Z"
  }
}