CVE-2026-42578

Year

2026

Published

May 13, 2026

Known Affected Devices

CVSS Score

N/A

What is CVE-2026-42578?

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.

FAQ

How severe is CVE-2026-42578?

CVE-2026-42578 has a CVSS score of N/A/10, rated as Unknown. Review the affected products list and apply vendor patches.

What does the CVSS score mean for CVE-2026-42578?

CVSS (Common Vulnerability Scoring System) rates vulnerability severity from 0.0 to 10.0. CVE-2026-42578 scores N/A/10 (Unknown). Scores 9.0–10.0 are Critical, 7.0–8.9 are High, 4.0–6.9 are Medium, and below 4.0 are Low.

Which devices are affected by CVE-2026-42578?

The list of devices confirmed to be affected by CVE-2026-42578 is shown in the "Affected Devices" section above. Check your firmware version against the vendor security advisory and apply the latest patch.

How do I fix or mitigate CVE-2026-42578?

Apply the latest firmware or software update from the vendor. Check the References section above for official advisories and patch notes. If no patch is available, consider disabling the affected feature or isolating the device from untrusted networks.