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

Affected: netty, Red Hat Cryostat 4 on RHEL 9, Red Hat build of Apache Camel 4.18.1.P1 for Spring Boot 3.5.16, Red Hat build of Quarkus 3.27.4, Red Hat build of Quarkus 3.33.2, Red Hat JBoss Enterprise Application Platform 7.4 ELS on RHEL 7, Red Hat JBoss Enterprise Application Platform 7.4 ELS on RHEL 8, Red Hat JBoss Enterprise Application Platform 7.4 ELS on RHEL 9, Red Hat JBoss Enterprise Application Platform 8.1.7.GA, Red Hat JBoss Enterprise Application Platform 8.1 for RHEL 10 and 21 more

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.

USN-8401-1 — netty vulnerabilities

Affected: Ubuntu:Pro:14.04:LTS: netty, Ubuntu:Pro:16.04:LTS: netty, Ubuntu:Pro:18.04:LTS: netty, Ubuntu:Pro:20.04:LTS: netty, Ubuntu:Pro:22.04:LTS: netty, Ubuntu:Pro:24.04:LTS: netty, Ubuntu:Pro:26.04:LTS: netty

It was discovered that Netty's HTTP proxy handler did not properly validate headers when constructing CONNECT requests. An attacker could possibly use this issue to inject arbitrary HTTP headers into CONNECT requests. This issue only affected Ubuntu 18.04 LTS, Ubuntu 20.04 LTS, Ubuntu 22.04 LTS, Ubuntu 24.04 LTS, and Ubuntu 26.04 LTS. (CVE-2026-42578)

It was discovered that Netty's DNS codec did not properly enforce domain name constraints. An attacker could possibly use this issue to bypass domain name validation, or cause Netty to consume resources, leading to a denial of service. This issue only affected Ubuntu 20.04 LTS, Ubuntu 22.04 LTS, Ubuntu 24.04 LTS, and Ubuntu 26.04 LTS. (CVE-2026-42579)

It was discovered that Netty did not correctly handle HTTP/1.0 requests containing both a Transfer-Encoding and Content-Length header. A remote attacker could possibly use this issue to perform HTTP request smuggling attacks. (CVE-2026-42581)

Violeta Georgieva discovered that Netty incorrectly paired responses with requests when handling informational HTTP responses. A remote attacker could possibly use this issue to perform HTTP request smuggling attacks. (CVE-2026-42584)

Violeta Georgieva discovered that Netty incorrectly parsed malformed Transfer-Encoding headers. A remote attacker could possibly use this issue to perform HTTP request smuggling attacks. (CVE-2026-42585)

It was discovered that Netty's Redis encoder did not validate CRLF characters. An attacker could possibl…

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

USN-8401-1 — netty vulnerabilities