CVE-2026-42578
HIGHDescription
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.
How to fix
This vulnerability affects an unusually large number of packages. The highest-confidence fixes are shown above; the full list is longer. Check the referenced advisories for complete coverage.
TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works
Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Exploit Intelligence
Moderate risk: more likely to be exploited than 62% of all known CVEs.
References
Related Vulnerabilities
Other CWE-113 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2022-37436 | Medium | 5.3 | 58% | - | Fix |
| CVE-2024-52875 | High | 8.8 | 30% | - | - |
| CVE-2016-5699 | Medium | 6.1 | 9.9% | - | Fix |
| CVE-2016-8024 | High | 8.1 | 8.7% | - | - |
| CVE-2017-17742 | Medium | 5.3 | 5.6% | - | Fix |
| CVE-2016-5325 | Medium | 6.1 | 4.1% | - | Fix |
Common questions
How do I fix CVE-2026-42578?
Published advisories record a fix for 336 affected products. The "How to fix" section on this page lists the fixed version and source advisory for each one, so apply the entry matching what you actually run.
Is CVE-2026-42578 being actively exploited?
Not that we know of. CVE-2026-42578 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 1.1% is the estimated probability that it will be exploited in the next 30 days. That is higher than 62% of all scored CVEs.
How severe is CVE-2026-42578?
CVE-2026-42578 has a CVSS v3 base score of 7.5, rated high. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
What does CVE-2026-42578 affect?
Published advisories record a fix for cryostat/cryostat (Red Hat / RHEL), cryostat/cryostat (Rocky), cryostat/cryostat-agent (Red Hat / RHEL), cryostat/cryostat-agent (Rocky), and 332 more. Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-08-13.