CVE-2026-47691
HighCVSS 8.7Exploitation Probability (EPSS)
Low risk21th percentile - higher than 21% of all known CVEs
Summary
A vulnerability in Netty's `DnsResolveContext` allows DNS Cache Poisoning due to insufficient validation of NS record bailiwick. An attacker controlling an authoritative DNS server for a subdomain can inject fake A records for parent domains into the cache, redirecting traffic.
Risk Assessment
The organization is at risk of DNS Cache Poisoning attacks, potentially leading to traffic redirection to malicious servers, data theft, or session hijacking. Applications using Netty for DNS resolution are affected.
Recommendation
Upgrade Netty to version 4.1.135.Final or 4.2.15.Final immediately. If an upgrade is not possible, consider using an external DNS resolver with bailiwick validation.
Original NVD description (English source)
Netty is a network application framework for development of protocol servers and clients. Prior to versions 4.1.135.Final and 4.2.15.Final, Netty's `DnsResolveContext` insufficiently validates the bailiwick of NS records, enabling DNS Cache Poisoning. An attacker controlling an authoritative name server for a subdomain can poison the cache for parent domains (like `.co.uk`). In `io.netty.resolver.dns.DnsResolveContext.AuthoritativeNameServerList#add` method accepts any NS record from the AUTHORITY section as long as the record's name is a suffix of the questionName. Subsequently, the `handleWithAdditional` method caches the associated A records from the ADDITIONAL section directly into the `authoritativeDnsServerCache` under the parent domain's key. This bypasses standard bailiwick rules, where a server authoritative for a subdomain should not be trusted to provide authoritative records for its parent. The poisoned cache is then used for all future resolutions under the parent domain's key. Versions 4.1.135.Final and 4.2.15.Final patch the issue.