High severity · published May 13, 2026
CVE-2026-42578
Netty: HTTP Header Injection via HttpProxyHandler Disabled Validation
7.5
CVSS
1.1%
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 HttpProxyHandler constructs HTTP CONNECT requests with header validation explicitly disabled. The newInitialMessage() method creates headers using DefaultHttpHeadersFactory.headersFactory().withValidation(false), then adds user-provided outboundHeaders without any CRLF validation. This allows an attacker who can influence the outbound headers to inject arbitrary HTTP headers into the CONNECT request sent to the proxy server. 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:N
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
High
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)1.1% · higher than 65% 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 AMQ Broker 7.13.6 · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat AMQ Broker 7.14.1 · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat AMQ Clients · 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 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
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-42578
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-42578
Exploit
https://github.com/netty/netty/security/advisories/GHSA-45q3-82m4-75jr
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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