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Vulnerability · Published May 13, 2026 · Assigned by GitHub_M

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

High 7.5

In plain English

A high-severity improper input validation in netty from netty. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 1.0% (higher than 63% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)7.5High
Exploit odds (30 days)1.0%top 36.8% of all CVEs
Exploited in the wildNo reportsCISA SSVC: poc
Attack toolingNoneno public tooling known

Official 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 packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:12nettyno fix listedDEBIAN-CVE-2026-42579
Debian:13nettyno fix listedDEBIAN-CVE-2026-42579
Debian:14nettyno fix listedDEBIAN-CVE-2026-42579
Mavenio.netty:netty-codec-dns4.1.133.FinalGHSA-cm33-6792-r9fm
Mavenio.netty:netty-codec-dns4.2.13.FinalGHSA-cm33-6792-r9fm
Ubuntu:25.10nettyno fix listedUBUNTU-CVE-2026-42579
Ubuntu:26.10nettyno fix listedUBUNTU-CVE-2026-42579

Affected products (as reported)

VendorProductVersions
netty netty >= 4.2.0.Alpha1, < 4.2.13.Final< 4.1.133.Final

Weakness: CWE-20, CWE-400, CWE-626, CWE-1286 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

References