Vulnerability · Published Jun 12, 2026 · Assigned by GitHub_M

CVE-2026-45673Netty: DNS Cache Poisoning due to Predictable PRNG and Default Static Source Port

Medium 6.8

In plain English

A medium-severity weak randomness in netty from netty. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 25% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)6.8Medium

Exploit odds (30 days)0.3%top 74.8% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

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 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). Versions 4.1.135.Final and 4.2.15.Final patch the issue.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Debian:12	netty	no fix listed	DEBIAN-CVE-2026-45673
Debian:13	netty	no fix listed	DEBIAN-CVE-2026-45673
Debian:14	netty	no fix listed	DEBIAN-CVE-2026-45673
Maven	io.netty:netty-resolver-dns	4.1.135.Final	GHSA-xmv7-r254-6q78
Maven	io.netty:netty-resolver-dns	4.2.15.Final	GHSA-xmv7-r254-6q78
Ubuntu:25.10	netty	no fix listed	UBUNTU-CVE-2026-45673
Ubuntu:26.10	netty	no fix listed	UBUNTU-CVE-2026-45673

Affected products (as reported)

Vendor	Product	Versions
netty	netty	>= 4.2.0.Final, < 4.2.15.Final< 4.1.135.Final

Weakness: CWE-330, CWE-340 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:H/A:N

References

https://github.com/netty/netty/security/advisories/GHSA-xmv7-r254-6q78 x_refsource_CONFIRM
https://github.com/netty/netty/releases/tag/netty-4.1.135.Final x_refsource_MISC
https://github.com/netty/netty/releases/tag/netty-4.2.15.Final x_refsource_MISC