Answer in brief
CVE-2026-47691 records a High severity (CVSS 8.7) vulnerability in Netty has Insufficient Bailiwick Validation for NS Records. The current sources do not mark it as known exploited. The current feed maps netty/netty (generic), io.netty:netty-resolver-dns (maven), io.netty:netty-resolver-dns (maven), io.netty:netty-resolver-dns (maven) and additional mapped packages. Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 8.7. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps netty/netty (generic), io.netty:netty-resolver-dns (maven), io.netty:netty-resolver-dns (maven), io.netty:netty-resolver-dns (maven) and additional mapped packages. Check affected ranges and fixed versions before updating.
| Product | Affected versions | Fixed versions |
|---|---|---|
| cpe:2.3:a:netty:netty:*:*:*:*:*:*:*:* | Not reported | Not reported |
| Package | Affected range | Fixed version |
|---|---|---|
| netty/nettygeneric | >= 4.2.0.Final, < 4.2.15.Final || < 4.1.135.Final | Not reported |
| io.netty:netty-resolver-dnsmaven | >=4.2.0.Final <4.2.15.Final | 4.2.15.Final |
| io.netty:netty-resolver-dnsmaven | >=4.2.0.Final,<=4.2.14.Final | 4.2.15.Final |
| io.netty:netty-resolver-dnsmaven | <=4.1.134.Final | 4.1.135.Final |
| io.netty:netty-resolver-dnsmaven | >=0 <4.1.135.Final | 4.1.135.Final |
Published upstream
Jun 12, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Sep 17, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Jun 11, 2026
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.
Quoted source text, attributed separately from HOL analysis.