Critical severity · published May 13, 2026
CVE-2026-42579
Netty: DNS Codec Input Validation Bypass in Netty (Encoder + Decoder)
9.1
CVSS
1%
EPSS
No
On KEV
Description
Netty is an asynchronous, event-driven network application framework. Prior to 4.2.13.Final and 4.1.133.Final, Netty's DNS codec does not enforce RFC 1035 domain name constraints during either encoding or decoding. This creates a bidirectional attack surface: malicious DNS responses can exploit the decoder, and user-influenced hostnames can exploit the encoder. This vulnerability is fixed in 4.2.13.Final and 4.1.133.Final.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
High
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)1.0% · higher than 63% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
NE
netty · netty
>= 4.2.0.Alpha1, < 4.2.13.Final; < 4.1.133.Final · source: vendor, NVD
C4
Cryostat 4 on RHEL 9 · Red Hat
All versions, or not specified · source: CISA
OS
OpenShift Serverless · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat Build of Keycloak · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat Data Grid 8 · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat Enterprise Linux AI (RHEL AI) 3 · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat Fuse 7 · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat JBoss Enterprise Application Platform 7.4 ELS on RHEL 7 · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat JBoss Enterprise Application Platform 7.4 ELS on RHEL 8 · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat JBoss Enterprise Application Platform 7.4 ELS on RHEL 9 · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat JBoss Enterprise Application Platform 8.1 for RHEL 10 · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat JBoss Enterprise Application Platform 8.1 for RHEL 8 · Red Hat
All versions, or not specified · source: CISA
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-42579
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-42579
Exploit
https://github.com/netty/netty/security/advisories/GHSA-cm33-6792-r9fm
access.redhat.com
https://access.redhat.com/errata/RHSA-2026:23808
access.redhat.com
https://access.redhat.com/errata/RHSA-2026:24502
access.redhat.com
https://access.redhat.com/errata/RHSA-2026:25123
access.redhat.com
https://access.redhat.com/errata/RHSA-2026:28010
access.redhat.com
https://access.redhat.com/errata/RHSA-2026:36820
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