CVE-2026-45673 Netty: DNS Cache Poisoning due to Predictable PRNG and Default Static Source Port
Netty's predictable DNS transaction IDs and static source ports allow attackers to perform DNS cache poisoning, requiring an upgrade to patched versions.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-45673?
CVE-2026-45673 is a medium-severity vulnerability in Netty Netty, published on 12 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
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.
Which versions are affected by CVE-2026-45673?
4 open source packages ship an affected version, including io.netty:netty-resolver-dns. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
io.netty:netty-resolver-dns Maven | All versions | 4.1.135.Final |
io.netty:netty-resolver-dns Maven | All versions | 4.1.135.Final |
io.netty:netty-resolver-dns Maven | From 4.2.0.Final | 4.2.15.Final |
io.netty:netty-resolver-dns Maven | From 4.2.0.Final | 4.2.15.Final |
Products include Netty Netty.
How do I fix CVE-2026-45673?
Upgrade io.netty:netty-resolver-dns to a fixed version for your release line: 4.1.135.Final or 4.2.15.Final.
Is CVE-2026-45673 being exploited?
There is no known exploitation of CVE-2026-45673 in the wild and no public exploit code.
Other vulnerabilities in Netty Netty
- CVE-2026-75595 Netty: SNI Routing Bypass via Fragmented TLS ClientHello Causing Fallback to Default SslContext
- CVE-2026-75596 Netty: Fragmented ClientHello records trigger quadratic pre-handshake reassembly in default SNI parsing
- CVE-2026-59901 Netty Bzip2Decoder: Infinite Loop in RLE State Machine Leads to Event-Loop Thread Hang
- CVE-2026-55851 Netty codec-haproxy: Signed-Byte Sentinel Collision in HAProxyMessageDecoder Leads to Unbounded Memory Exhaustion
- CVE-2026-56745 Netty SpdyHttpDecoder: ByteBuf Reference Leak on RST_STREAM Leads to Native Memory Exhaustion
Sources
Also known as CLEANSTART-2026-GK86631, CLEANSTART-2026-MH05121, CLEANSTART-2026-RE47294, CLEANSTART-2026-XD15428, DEBIAN-CVE-2026-45673, ECHO-f9b6-33d0-f377 and 66 more.