Vulnerabilities in pkg:maven/io.netty/netty-resolver-dns

PACKAGE
Advisory Identifier: GHSA-5pvg-856g-cp85
Advisory Summary

CVE-2026-47691 is a HIGH (CVSS 8.7) netty has insufficient bailiwick validation vulnerability (CWE-345: Insufficient Verification of Data Authenticity) affecting Netty resolver dns libraries in the Maven ecosystem. The issue involves netty has insufficient bailiwick validation for ns records. Remediation is available by upgrading affected packages to version 4.2.15.Final, 4.1.135.Final.

3 Known Advisory Record(s)
Package Vulnerability Intelligence

pkg:maven/io.netty/netty-resolver-dns

3 Known Advisory Record(s)

Vulnerability advisories affecting package pkg:maven/io.netty/netty-resolver-dns. Select an advisory below to view technical details or fixes.

Advisory ID CVE / NVD Severity Summary
GHSA-5pvg-856g-cp85 CVE-2026-47691 HIGH Netty has Insufficient Bailiwick Validation for NS Records
GHSA-676x-f7gg-47vc CVE-2026-45674 HIGH Netty Vulnerable to DNS Cache Poisoning via Missing Bailiwick Checks in CNAME Records
GHSA-xmv7-r254-6q78 CVE-2026-45673 MODERATE Netty: DNS Cache Poisoning due to Predictable PRNG and Default Static Source Port

CVE-2026-47691 at a Glance

CVE Identifier CVE-2026-47691
GHSA Identifier GHSA-5pvg-856g-cp85
Severity HIGH
CVSS v3.1 Base Score 8.7
CWE Classification CWE-345: Insufficient Verification of Data Authenticity
Affected Product Netty resolver dns
Package Ecosystem Maven
Published Date
Last Updated

Security Impact

CVSS: 8.7

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:C/C:H/I:H/A:N).

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

How to Fix CVE-2026-47691

To remediate this vulnerability, upgrade all affected Netty resolver dns 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.netty:netty-resolver-dns fixed: 4.2.15.Final
<dependency>
    <groupId>io.netty</groupId>
    <artifactId>netty-resolver-dns</artifactId>
    <version>4.2.15.Final</version>
</dependency>
io.netty:netty-resolver-dns fixed: 4.1.135.Final
<dependency>
    <groupId>io.netty</groupId>
    <artifactId>netty-resolver-dns</artifactId>
    <version>4.1.135.Final</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.netty

How to Check if You Are Affected

To determine whether your Java application is affected by CVE-2026-47691, inspect your build dependencies using the Maven Dependency Plugin:

mvn dependency:tree -Dincludes=io.netty

Analyze the terminal output to locate any version of Netty resolver dns in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 4.2.15.Final), your application is affected.

Note: The mvn dependency:tree -Dincludes=io.netty 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-345: Insufficient Verification of Data Authenticity, where the product does not sufficiently verify the origin or authenticity of data, in a way that causes it to accept invalid data. In Netty resolver dns, 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

### Summary Netty's `DnsResolveContext` insufficiently validates the bailiwick of NS records, enabling DNS Cache Poisoning. An attacker controlling an authoritative name server for a subdomain can poison the cache for parent domains (like `.co.uk`). ### Details In `io.netty.resolver.dns.DnsResolveContext.AuthoritativeNameServerList#add` method accepts any NS record from the AUTHORITY section as long as the record's name is a suffix of the questionName. This means if the resolver queries evil.co.uk., it will accept an NS record claiming authority over co.uk.. Subsequently, the `handleWithAdditional` method caches the associated A records from the ADDITIONAL section directly into the `authoritativeDnsServerCache` under the parent domain's key (co.uk.). This bypasses standard bailiwick rules, where a server authoritative for a subdomain should not be trusted to provide authoritative records for its parent. The poisoned cache is then used for all future resolutions under co.uk.. The `io.netty.resolver.dns.DnsResolveContext.AuthoritativeNameServerList#cache` method only prevents caching if the record is for the root zone (dots == 1). ### Impact DNS Cache Poisoning. Any application using Netty's DNS resolver is impacted.

CVE-2026-47691 Affected Netty resolver dns Versions

2 component(s)
Fixed Versions:
4.2.15.Final4.1.135.Final
Product / Package Ecosystem Affected Versions Fixed Version
io.netty:netty-resolver-dns
Maven
≥ 4.2.0.Final
< 4.2.15.Final
4.2.15.Final
io.netty:netty-resolver-dns
Maven
< 4.1.135.Final
4.1.135.Final

References

GitHub Advisory / Wiki ADVISORY
https://github.com/netty/netty/security/advisories/GHSA-5pvg-856g-cp85
NVD — CVE-2026-47691 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-47691
Netty resolver dns Security Information SECURITY
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-47691.json
Netty resolver dns Release RELEASE
https://github.com/netty/netty/releases/tag/netty-4.2.15.Final
Netty resolver dns Release RELEASE
https://github.com/netty/netty/releases/tag/netty-4.1.135.Final
Netty resolver dns Source Repository REPOSITORY
https://github.com/netty/netty
bugzilla.redhat.com/show_bug.cgi WEB
https://bugzilla.redhat.com/show_bug.cgi?id=2488439
Netty resolver dns Security Information SECURITY
https://access.redhat.com/security/cve/CVE-2026-47691
access.redhat.com/errata/rhsa-2026:65... WEB
https://access.redhat.com/errata/RHSA-2026:65126
access.redhat.com/errata/rhsa-2026:62... WEB
https://access.redhat.com/errata/RHSA-2026:62260
access.redhat.com/errata/rhsa-2026:54... WEB
https://access.redhat.com/errata/RHSA-2026:54435
access.redhat.com/errata/rhsa-2026:53... WEB
https://access.redhat.com/errata/RHSA-2026:53806
access.redhat.com/errata/rhsa-2026:53... WEB
https://access.redhat.com/errata/RHSA-2026:53646
access.redhat.com/errata/rhsa-2026:53... WEB
https://access.redhat.com/errata/RHSA-2026:53645
access.redhat.com/errata/rhsa-2026:53... WEB
https://access.redhat.com/errata/RHSA-2026:53644
access.redhat.com/errata/rhsa-2026:50... WEB
https://access.redhat.com/errata/RHSA-2026:50085
access.redhat.com/errata/rhsa-2026:49... WEB
https://access.redhat.com/errata/RHSA-2026:49701
access.redhat.com/errata/rhsa-2026:49... WEB
https://access.redhat.com/errata/RHSA-2026:49700
access.redhat.com/errata/rhsa-2026:48... WEB
https://access.redhat.com/errata/RHSA-2026:48151
access.redhat.com/errata/rhsa-2026:41... WEB
https://access.redhat.com/errata/RHSA-2026:41951
access.redhat.com/errata/rhsa-2026:37... WEB
https://access.redhat.com/errata/RHSA-2026:37390
access.redhat.com/errata/rhsa-2026:34... WEB
https://access.redhat.com/errata/RHSA-2026:34608
access.redhat.com/errata/rhsa-2026:26... WEB
https://access.redhat.com/errata/RHSA-2026:26586
access.redhat.com/errata/rhsa-2026:26... WEB
https://access.redhat.com/errata/RHSA-2026:26018
access.redhat.com/errata/rhsa-2026:26... WEB
https://access.redhat.com/errata/RHSA-2026:26017

Frequently Asked Questions

What is CVE-2026-47691?
CVE-2026-47691 is a security vulnerability in Netty resolver dns involving Netty has Insufficient Bailiwick Validation for NS Records under CWE-345: Insufficient Verification of Data Authenticity.
Which Netty resolver dns versions are affected?
Affected versions include releases prior to 4.2.15.Final, 4.1.135.Final across affected packages: io.netty:netty-resolver-dns.
What version fixes CVE-2026-47691?
Upgrading to 4.2.15.Final, 4.1.135.Final (or the latest patched release for your respective branch) resolves the vulnerability.
Is netty-resolver-dns affected?
Yes, io.netty:netty-resolver-dns is affected in releases prior to 4.2.15.Final, 4.1.135.Final. Upgrade your dependency to 4.2.15.Final, 4.1.135.Final or later.
What is the CVSS score of CVE-2026-47691?
CVE-2026-47691 has a CVSS v3.1 base score of 8.7 (HIGH) with vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N.
What CWE is associated with CVE-2026-47691?
CVE-2026-47691 is classified under CWE-345: Insufficient Verification of Data Authenticity (The product does not sufficiently verify the origin or authenticity of data, in a way that causes it to accept invalid data.).
How can I check Maven dependencies for CVE-2026-47691?
Run the dependency tree command: 'mvn dependency:tree -Dincludes=io.netty'. 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
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  "id" : "GHSA-5pvg-856g-cp85",
  "modified" : "2026-09-18T15:31:39Z",
  "published" : "2026-06-08T23:02:48Z",
  "aliases" : [ "CVE-2026-47691" ],
  "summary" : "Netty has Insufficient Bailiwick Validation for NS Records",
  "details" : "### Summary\nNetty's `DnsResolveContext` insufficiently validates the bailiwick of NS records, enabling DNS Cache Poisoning. An attacker controlling an authoritative name server for a subdomain can poison the cache for parent domains (like `.co.uk`).\n\n### Details\nIn `io.netty.resolver.dns.DnsResolveContext.AuthoritativeNameServerList#add` method accepts any NS record from the AUTHORITY section as long as the record's name is a suffix of the questionName.\n\nThis means if the resolver queries evil.co.uk., it will accept an NS record claiming authority over co.uk.. Subsequently, the `handleWithAdditional` method caches the associated A records from the ADDITIONAL section directly into the `authoritativeDnsServerCache` under the parent domain's key (co.uk.). This bypasses standard bailiwick rules, where a server authoritative for a subdomain should not be trusted to provide authoritative records for its parent. The poisoned cache is then used for all future resolutions under co.uk..\n\nThe `io.netty.resolver.dns.DnsResolveContext.AuthoritativeNameServerList#cache` method only prevents caching if the record is for the root zone (dots == 1).\n\n### Impact\nDNS Cache Poisoning. Any application using Netty's DNS resolver is impacted.",
  "severity" : [ {
    "type" : "CVSS_V3",
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    "url" : "https://access.redhat.com/errata/RHSA-2026:53806"
  }, {
    "type" : "WEB",
    "url" : "https://access.redhat.com/errata/RHSA-2026:53646"
  }, {
    "type" : "WEB",
    "url" : "https://access.redhat.com/errata/RHSA-2026:53645"
  }, {
    "type" : "WEB",
    "url" : "https://access.redhat.com/errata/RHSA-2026:53644"
  }, {
    "type" : "WEB",
    "url" : "https://access.redhat.com/errata/RHSA-2026:50085"
  }, {
    "type" : "WEB",
    "url" : "https://access.redhat.com/errata/RHSA-2026:49701"
  }, {
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    "url" : "https://access.redhat.com/errata/RHSA-2026:49700"
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    "url" : "https://access.redhat.com/errata/RHSA-2026:48151"
  }, {
    "type" : "WEB",
    "url" : "https://access.redhat.com/errata/RHSA-2026:41951"
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  "database_specific" : {
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    "severity" : "HIGH",
    "github_reviewed" : true,
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    "nvd_published_at" : "2026-06-12T16:16:30Z"
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}