Netty <=4.1.135/<=4.2.15 DNS ByteBuf Leak via Malformed IDN
CVE-2026-73508 Published on August 13, 2026
Netty: Memory Leak in DNS Record Decoder via Malformed Domain Names
Netty is an asynchronous, event-driven network application framework. Prior to 4.1.136.Final and 4.2.16.Final, io.netty.handler.codec.dns.AbstractDnsRecord, io.netty.handler.codec.dns.DefaultDnsRecordDecoder.decodeRecord(), and io.netty.handler.codec.dns.DnsCodecUtil.decompressDomainName() failed to release retained or newly allocated ByteBuf objects when IDN.toASCII() or encodeDomainName() rejected a malformed domain name, allowing unauthenticated remote DNS packets to leak direct memory incrementally until denial of service. This issue is fixed in versions 4.1.136.Final and 4.2.16.Final.
Vulnerability Analysis
CVE-2026-73508 is exploitable with network access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality and integrity, and a small impact on availability.
Weakness Type
Missing Release of Resource after Effective Lifetime
The software does not release a resource after its effective lifetime has ended, i.e., after the resource is no longer needed. When a resource is not released after use, it can allow attackers to cause a denial of service by causing the allocation of resources without triggering their release. Frequently-affected resources include memory, CPU, disk space, power or battery, etc.
Products Associated with CVE-2026-73508
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Affected Versions
netty:- Version < 4.1.136.Final is affected.
- Version >= 4.2.0.Final, < 4.2.16.Final is affected.