CVE-2026-47691: Io.netty:netty resolver dns: Netty has Insufficient Bailiwick Validation for NS Records
Affects io.netty:netty-resolver-dnsSource GCVE Database
Not known to be exploited · CVSS 8.7 High : upgrade to 4.2.15.Final soon.
Data as of 30 Oct 2026, 06:59 UTC
- EPSS
- 0.3% chance of exploitation in 30 days – higher than 31% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 4.2.15.Final, 4.1.135.Final
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:NExploitation evidence
Disclosed: evidence found.
CVE published 8 Jun 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.
What to do
Upgrade io.netty:netty-resolver-dns to 4.2.15.Final; io.netty:netty-resolver-dns to 4.1.135.Final.
Patches and advisories
- access.redhat.com/errata/RHSA-2026:65126 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:62260 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:54435 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:53806 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:53646 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:53645 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:53644 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:50085 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:49701 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:49700 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:48151 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:41951 (opens in a new tab)
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| Mavenio.netty:netty-resolver-dns | Affected
| Fixed in
|
| Mavenio.netty:netty-resolver-dns | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
Description
### Summary 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`). ### Details 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. This means if the resolver queries evil.co.uk., it will accept an NS record claiming authority over co.uk.. Subsequently, the `handleWithAdditional` method caches the associated A records from the ADDITIONAL section directly into the `authoritativeDnsServerCache` under the parent domain's key (co.uk.). 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 co.uk.. The `io.netty.resolver.dns.DnsResolveContext.AuthoritativeNameServerList#cache` method only prevents caching if the record is for the root zone (dots == 1). ### Impact DNS Cache Poisoning. Any application using Netty's DNS resolver is impacted.
References
- github.com/netty/netty/security/advisories/GHSA-5pvg-856g-cp85 (opens in a new tab)
- nvd.nist.gov/vuln/detail/CVE-2026-47691 (opens in a new tab)
- security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-47691.json (opens in a new tab)
- github.com/netty/netty/releases/tag/netty-4.2.15.Final (opens in a new tab)
- github.com/netty/netty/releases/tag/netty-4.1.135.Final (opens in a new tab)
- github.com/netty/netty (opens in a new tab)
- bugzilla.redhat.com/show_bug.cgi?id=2488439 (opens in a new tab)
- access.redhat.com/security/cve/CVE-2026-47691 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:65126 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:62260 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:54435 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:53806 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:53646 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:53645 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:53644 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:50085 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:49701 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:49700 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:48151 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:41951 (opens in a new tab)