What’s Vulnerable › Vulnerabilities

CVE-2026-42579: Netty: DNS Codec Input Validation Bypass in Netty (Encoder + Decoder)

• Severity: critical (CVSS 9.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.0% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-05-13 · updated 2026-09-18
• Weakness: CWE-20

Description

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.

Affected products

• netty: before 4.1.133; from 4.2.0 before 4.2.13 — fixed in 4.1.133, 4.2.13

How to fix

Upgrade to a fixed version: netty 4.1.133, 4.2.13. Check the vendor advisory for mitigations.

References

• https://github.com/netty/netty/security/advisories/GHSA-cm33-6792-r9fm
• https://access.redhat.com/errata/RHSA-2026:23808
• https://access.redhat.com/errata/RHSA-2026:24502
• https://access.redhat.com/errata/RHSA-2026:25123
• https://access.redhat.com/errata/RHSA-2026:28010
• https://access.redhat.com/errata/RHSA-2026:36820
• https://access.redhat.com/errata/RHSA-2026:37390
• https://access.redhat.com/errata/RHSA-2026:49700
• https://access.redhat.com/errata/RHSA-2026:49701
• https://access.redhat.com/errata/RHSA-2026:53644
• https://access.redhat.com/errata/RHSA-2026:53645
• https://access.redhat.com/errata/RHSA-2026:53646

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