Netty: DNS Codec Input Validation Bypass in Netty (Encoder + Decoder)
Netty is an asynchronous, event-driven network application framework. Prior to 4.2.13.Final and 4.1.133.Final, Netty's DNS codec does not enforce RFC 1035 domain name constraints during either encoding or decoding. This creates a bidirectional attack surface: malicious DNS responses can exploit the decoder, and user-influenced hostnames can exploit the encoder. This vulnerability is fixed in 4.2.13.Final and 4.1.133.Final.
- Published
- May 13, 2026
- Updated
- Sep 18, 2026
- EPSS
- 0.8% · 56th percentile
- CWE
- CWE-20
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Report tools
Action score
36
Monitor
Low priority for now.
- CVSS
- 36 / 40 · 9.1 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.8%
CISA SSVC decision
- Exploitation
- proof of concept
- Automatable
- yes
- Technical impact
- partial
Vulnrichment: CISA's decision-tree inputs.
CNA vs NVD score
- NVD
- 9.1
- CNA · GitHub_M
- 7.5
- 1.6 point gap
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.
Affected systems
| Vendor | Product | CPE |
|---|---|---|
| netty | netty | cpe:2.3:a:netty:netty |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- netty nettybefore 4.1.133
- netty netty4.2.0 and later · before 4.2.13
Versions reported by the vendor
Affected version ranges reported by the assigning authority (GitHub_M). Independent of NVD's CPE analysis and usually ahead of it.
netty netty
- >= 4.2.0.Alpha1, < 4.2.13.Final, < 4.1.133.Finalaffected
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Debian:12 | netty | all versions | — |
| Maven | io.netty:netty-codec-dns | from 4.2.0.Alpha1 · before 4.2.13.Final | 4.2.13.Final |
| Maven | io.netty:netty-codec-dns | before 4.1.133.Final | 4.1.133.Final |
| openSUSE:Tumbleweed | netty | before 4.1.133-1.1 | 4.1.133-1.1 |
| Red Hat:jboss_enterprise_application_platform_els:7.4::el7 | eap7-activemq-artemis | before 0:2.16.0-22.redhat_00057.1.el7eap | 0:2.16.0-22.redhat_00057.1.el7eap |
| Red Hat:jboss_enterprise_application_platform_els:7.4::el7 | eap7-activemq-artemis-cli | before 0:2.16.0-22.redhat_00057.1.el7eap | 0:2.16.0-22.redhat_00057.1.el7eap |
| Red Hat:jboss_enterprise_application_platform_els:7.4::el7 | eap7-activemq-artemis-commons | before 0:2.16.0-22.redhat_00057.1.el7eap | 0:2.16.0-22.redhat_00057.1.el7eap |
| Red Hat:jboss_enterprise_application_platform_els:7.4::el7 | eap7-activemq-artemis-core-client | before 0:2.16.0-22.redhat_00057.1.el7eap | 0:2.16.0-22.redhat_00057.1.el7eap |
| Red Hat:jboss_enterprise_application_platform_els:7.4::el7 | eap7-activemq-artemis-dto | before 0:2.16.0-22.redhat_00057.1.el7eap | 0:2.16.0-22.redhat_00057.1.el7eap |
| Red Hat:jboss_enterprise_application_platform_els:7.4::el7 | eap7-activemq-artemis-hornetq-protocol | before 0:2.16.0-22.redhat_00057.1.el7eap | 0:2.16.0-22.redhat_00057.1.el7eap |
| Red Hat:jboss_enterprise_application_platform_els:7.4::el7 | eap7-activemq-artemis-hqclient-protocol | before 0:2.16.0-22.redhat_00057.1.el7eap | 0:2.16.0-22.redhat_00057.1.el7eap |
| Red Hat:jboss_enterprise_application_platform_els:7.4::el7 | eap7-activemq-artemis-jdbc-store | before 0:2.16.0-22.redhat_00057.1.el7eap | 0:2.16.0-22.redhat_00057.1.el7eap |
| Red Hat:jboss_enterprise_application_platform_els:7.4::el7 | eap7-activemq-artemis-jms-client | before 0:2.16.0-22.redhat_00057.1.el7eap | 0:2.16.0-22.redhat_00057.1.el7eap |
| Red Hat:jboss_enterprise_application_platform_els:7.4::el7 | eap7-activemq-artemis-jms-server | before 0:2.16.0-22.redhat_00057.1.el7eap | 0:2.16.0-22.redhat_00057.1.el7eap |
| Red Hat:jboss_enterprise_application_platform_els:7.4::el7 | eap7-activemq-artemis-journal | before 0:2.16.0-22.redhat_00057.1.el7eap | 0:2.16.0-22.redhat_00057.1.el7eap |
| Red Hat:jboss_enterprise_application_platform_els:7.4::el7 | eap7-activemq-artemis-ra | before 0:2.16.0-22.redhat_00057.1.el7eap | 0:2.16.0-22.redhat_00057.1.el7eap |
| Red Hat:jboss_enterprise_application_platform_els:7.4::el7 | eap7-activemq-artemis-selector | before 0:2.16.0-22.redhat_00057.1.el7eap | 0:2.16.0-22.redhat_00057.1.el7eap |
| Red Hat:jboss_enterprise_application_platform_els:7.4::el7 | eap7-activemq-artemis-server | before 0:2.16.0-22.redhat_00057.1.el7eap | 0:2.16.0-22.redhat_00057.1.el7eap |
| Red Hat:jboss_enterprise_application_platform_els:7.4::el7 | eap7-activemq-artemis-service-extensions | before 0:2.16.0-22.redhat_00057.1.el7eap | 0:2.16.0-22.redhat_00057.1.el7eap |
| Red Hat:jboss_enterprise_application_platform_els:7.4::el7 | eap7-activemq-artemis-tools | before 0:2.16.0-22.redhat_00057.1.el7eap | 0:2.16.0-22.redhat_00057.1.el7eap |
| Red Hat:jboss_enterprise_application_platform_els:7.4::el7 | eap7-glassfish-jsf | before 0:2.3.14-11.SP11_redhat_00001.1.el7eap | 0:2.3.14-11.SP11_redhat_00001.1.el7eap |
| Red Hat:jboss_enterprise_application_platform_els:7.4::el7 | eap7-ironjacamar | before 0:1.5.26-2.Final_redhat_00001.1.el7eap | 0:1.5.26-2.Final_redhat_00001.1.el7eap |
| Red Hat:jboss_enterprise_application_platform_els:7.4::el7 | eap7-ironjacamar-common-api | before 0:1.5.26-2.Final_redhat_00001.1.el7eap | 0:1.5.26-2.Final_redhat_00001.1.el7eap |
| Red Hat:jboss_enterprise_application_platform_els:7.4::el7 | eap7-ironjacamar-common-impl | before 0:1.5.26-2.Final_redhat_00001.1.el7eap | 0:1.5.26-2.Final_redhat_00001.1.el7eap |
+96
Same product
netty: all recordsOther highest-scoring records for the same primary product.
- CVE-2026-47691Netty has Insufficient Bailiwick Validation for NS Records40Plan
- CVE-2026-45674Netty Vulnerable to DNS Cache Poisoning via Missing Bailiwick Checks in CNAME Records40Plan
- CVE-2019-20445HttpObjectDecoder.java in Netty before 4.1.44 allows a Content-Length header to be accompanied by a second Content-Length header, or by a Tr40Plan
- CVE-2026-42581Netty: HTTP/1.0 TE+CL Coexistence Bypasses Smuggling Sanitization39Monitor
- CVE-2019-20444HttpObjectDecoder.java in Netty before 4.1.44 allows an HTTP header that lacks a colon, which might be interpreted as a separate header with39Monitor
- CVE-2026-75595Netty: SNI Routing Bypass via Fragmented TLS ClientHello Causing Fallback to Default SslContext36Monitor
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| netty netty | 4.2.13.Final · description | Vendor (CNA) |
| Maven:io.netty:netty-codec-dns | 4.1.133.Final | Package registry (OSV) |
| Maven:io.netty:netty-codec-dns | 4.2.13.Final | Package registry (OSV) |
| opensuse:netty | 4.1.133-1.1 · openSUSE:Tumbleweed | Package registry (OSV) |
| red hat:eap8-eap-product-conf-parent | 0:801.7.1-1.GA_redhat_00001.1.el10eap · Red Hat:jboss_enterprise_application_platform:8.1::el10 | Package registry (OSV) |
| red hat:eap8-eap-product-conf-wildfly-ee-feature-pack | 0:801.7.1-1.GA_redhat_00001.1.el10eap · Red Hat:jboss_enterprise_application_platform:8.1::el10 | Package registry (OSV) |
| red hat:eap8-netty | 0:4.1.135-1.Final_redhat_00001.1.el10eap · Red Hat:jboss_enterprise_application_platform:8.1::el10 | Package registry (OSV) |
| red hat:eap8-netty-buffer | 0:4.1.135-1.Final_redhat_00001.1.el10eap · Red Hat:jboss_enterprise_application_platform:8.1::el10 | Package registry (OSV) |
| red hat:eap8-netty-codec | 0:4.1.135-1.Final_redhat_00001.1.el10eap · Red Hat:jboss_enterprise_application_platform:8.1::el10 | Package registry (OSV) |
| red hat:eap8-netty-codec-dns | 0:4.1.135-1.Final_redhat_00001.1.el10eap · Red Hat:jboss_enterprise_application_platform:8.1::el10 | Package registry (OSV) |
| red hat:eap8-netty-codec-http | 0:4.1.135-1.Final_redhat_00001.1.el10eap · Red Hat:jboss_enterprise_application_platform:8.1::el10 | Package registry (OSV) |
| red hat:eap8-netty-codec-socks | 0:4.1.135-1.Final_redhat_00001.1.el10eap · Red Hat:jboss_enterprise_application_platform:8.1::el10 | Package registry (OSV) |
| red hat:eap8-netty-common | 0:4.1.135-1.Final_redhat_00001.1.el10eap · Red Hat:jboss_enterprise_application_platform:8.1::el10 | Package registry (OSV) |
| red hat:eap8-netty-handler | 0:4.1.135-1.Final_redhat_00001.1.el10eap · Red Hat:jboss_enterprise_application_platform:8.1::el10 | Package registry (OSV) |
| red hat:eap8-netty-handler-proxy | 0:4.1.135-1.Final_redhat_00001.1.el10eap · Red Hat:jboss_enterprise_application_platform:8.1::el10 | Package registry (OSV) |
| red hat:eap8-netty-resolver | 0:4.1.135-1.Final_redhat_00001.1.el10eap · Red Hat:jboss_enterprise_application_platform:8.1::el10 | Package registry (OSV) |
| suse:netty | 4.1.133-150200.4.46.1 · SUSE:Linux Enterprise Module for Package Hub 15 SP7 | Package registry (OSV) |
| suse:netty-tcnative | 2.0.77-150200.3.39.1 · SUSE:Linux Enterprise Module for Development Tools 15 SP7 | Package registry (OSV) |
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
No dated events beyond publication.
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
No commit or PR link among the references.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
No credits in the CNA record.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
- CVE-2026-100663136 days apartNetty HTTP/1 CONNECT authority-form mistranslated to malformed HTTP/334Monitor
- CVE-2026-100664136 days apartNetty 4.2.2 through 4.2.17 HTTP/1 Host Header Authority Confusion34Monitor
- CVE-2025-24970457 days apartSslHandler doesn't correctly validate packets which can lead to native crash when using native SSLEngine31Monitor
- CVE-2026-76816103 days apartNetty: MQTT Topic Name and Client ID Validation Bypass14Monitor
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
Technical details
Attack conditions
- Anyone who can reach it over the internet can trigger it.
- No account or password is required.
- No user action is required.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- none
- Integrity
- high · data or configuration can be modified
- Availability
- high · the service can be disrupted
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- None
- Integrity impact
- High
- Availability impact
- High
Weakness class (CWE)
CWE-20 · Improper Input ValidationCVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H
nvd-primary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
Attack patterns (CAPEC)
- Buffer Overflow via Environment VariablesCAPEC-10likelihood: High · High
- Server Side Include (SSI) InjectionCAPEC-101likelihood: High · High
- Cross Zone ScriptingCAPEC-104likelihood: Medium · High
- Command Line Execution through SQL InjectionCAPEC-108likelihood: Low · Very High
- Object Relational Mapping InjectionCAPEC-109likelihood: Low · High
- SQL Injection through SOAP Parameter TamperingCAPEC-110likelihood: High · Very High
- Double EncodingCAPEC-120likelihood: Low · Medium
- Subverting Environment Variable ValuesCAPEC-13likelihood: High · Very High
ATT&CK techniques
- Obfuscated Files or InformationT1027
- Masquerading: Invalid Code SignatureT1036.001
- Steal Web Session CookieT1539
- Subvert Trust Controls: Code SigningT1553.002
- Impair Defenses:Impair Command History LoggingT1562.003
- Hijack Execution Flow:Dynamic Linker HijackingT1574.006
- Hijack Execution Flow:Path Interception by PATH Environment VariableT1574.007
Noroxi analysis
No Noroxi analysis for this record yet
We don't hand-write analysis for all 385,000+ vulnerabilities; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.
We use this product, ask for helpChange log
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
- access.redhat.com/errata/RHSA-2026:23808
- access.redhat.com/errata/RHSA-2026:24502
- access.redhat.com/errata/RHSA-2026:25123
- access.redhat.com/errata/RHSA-2026:28010
- access.redhat.com/errata/RHSA-2026:36820
- access.redhat.com/errata/RHSA-2026:37390
- access.redhat.com/errata/RHSA-2026:49700
- access.redhat.com/errata/RHSA-2026:49701
- access.redhat.com/errata/RHSA-2026:53644
- access.redhat.com/errata/RHSA-2026:53645
- access.redhat.com/errata/RHSA-2026:53646
- access.redhat.com/errata/RHSA-2026:54435
- access.redhat.com/errata/RHSA-2026:65126
- access.redhat.com/security/cve/CVE-2026-42579
- bugzilla.redhat.com/show_bug.cgi?id=2477217
- security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-42579.json
Vendor advisories and official records. Exploit/PoC links are deliberately left out.