GHSA-xmv7-r254-6q78

Netty's DNS resolver uses a predictable PRNG for generating DNS transaction IDs and defaults to a static UDP source port. This combination reduces the entropy of DNS queries, enabling DNS Cache Poisoning (Kaminsky attack).

Details

Two factors contribute to this vulnerability in io.netty.resolver.dns: - Predictable Query IDs: DnsQueryIdSpace manages 16-bit transaction IDs in buckets of 16,384 IDs. It initializes only the first bucket. When an ID is returned, it is pushed back into the bucket at a random index generated by java.util.concurrent.ThreadLocalRandom:

Random random = ThreadLocalRandom.current();
int insertionPosition = random.nextInt(count + 1);

Because ThreadLocalRandom is a predictable LCG and the resolver operates within a single bucket, the sequence of IDs is predictable once the PRNG state is mathematically recovered.

Default Static Source Port: DnsNameResolverBuilder defaults to a channelStrategy of ChannelPerResolver. This binds the DatagramChannel once, resulting in a static source port for all subsequent queries.

Combined, a static source port and predictable transaction IDs reduces the entropy required to secure DNS resolution against spoofing.

Impact

DNS Cache Poisoning. Downstream applications using the default Netty DNS resolver may connect to malicious IPs, leading to traffic interception or MitM attacks.

Database specific

{
    "github_reviewed": true,
    "github_reviewed_at": "2026-06-08T23:02:05Z",
    "nvd_published_at": "2026-06-12T15:16:27Z",
    "severity": "MODERATE",
    "cwe_ids": [
        "CWE-330",
        "CWE-340"
    ]
}

References

Affected packages

Maven / io.netty:netty-resolver-dns

Package

Name: io.netty:netty-resolver-dns; View open source insights on deps.dev
Purl: pkg:maven/io.netty/netty-resolver-dns

Affected ranges

Type: ECOSYSTEM
Events: Introduced

4.2.0.Final

Fixed

4.2.15.Final

Affected versions

4.*

4.2.0.Final

4.2.1.Final

4.2.2.Final

4.2.3.Final

4.2.4.Final

4.2.5.Final

4.2.6.Final

4.2.7.Final

4.2.8.Final

4.2.9.Final

4.2.10.Final

4.2.11.Final

4.2.12.Final

4.2.13.Final

4.2.14.Final

Database specific

source

"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/06/GHSA-xmv7-r254-6q78/GHSA-xmv7-r254-6q78.json"

last_known_affected_version_range

"<= 4.2.14.Final"

Maven / io.netty:netty-resolver-dns

Package

Name: io.netty:netty-resolver-dns; View open source insights on deps.dev
Purl: pkg:maven/io.netty/netty-resolver-dns

Affected ranges

Type: ECOSYSTEM
Events: Introduced

0Unknown introduced version / All previous versions are affected

Fixed

4.1.135.Final

Affected versions

4.*

4.1.0.Beta4

4.1.0.Beta5

4.1.0.Beta6

4.1.0.Beta7

4.1.0.Beta8

4.1.0.CR1

4.1.0.CR2

4.1.0.CR3

4.1.0.CR4

4.1.0.CR5

4.1.0.CR6

4.1.0.CR7

4.1.0.Final

4.1.1.Final

4.1.2.Final

4.1.3.Final

4.1.4.Final

4.1.5.Final

4.1.6.Final

4.1.7.Final

4.1.8.Final

4.1.9.Final

4.1.10.Final

4.1.11.Final

4.1.12.Final

4.1.13.Final

4.1.14.Final

4.1.15.Final

4.1.16.Final

4.1.17.Final

4.1.18.Final

4.1.19.Final

4.1.20.Final

4.1.21.Final

4.1.22.Final

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4.1.26.Final

4.1.27.Final

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4.1.128.Final

4.1.129.Final

4.1.130.Final

4.1.131.Final

4.1.132.Final

4.1.133.Final

4.1.134.Final

Database specific

source

"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/06/GHSA-xmv7-r254-6q78/GHSA-xmv7-r254-6q78.json"

last_known_affected_version_range

"<= 4.1.134.Final"