CVE-2026-47691

What it is

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.

At a glance

Exploitability

Can be exploited over the network without logging in. High risk of data exposure, data tampering.

Exploit odds

0.4% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2026-06-12 16:16 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-09-18 13:18 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 0.4% in the next 30 days (EPSS).
• Severity: 8.7 HIGH (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2026-06-12 16:16 UTC

Last modified

2026-09-18 13:18 UTC

Exploit probability

0.4% · EPSS, next 30 days

Weakness

CWE-345

Record status

Modified

Affected

• Netty < 4.1.135
• Netty < 4.2.15

Attack profile CVSS 3.1 · 8.7

Attack vector

Network

Complexity

High

Privileges needed

None

User interaction

None

Scope

Changed

Confidentiality

High

Integrity

High

Availability

None

Is it in your code?

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