Is CVE-2026-42578 actively exploited?

No active exploitation of CVE-2026-42578 has been confirmed so far. Continue monitoring, as exploit status can change.

Can CVE-2026-42578 be exploited remotely?

Yes. CVE-2026-42578 is exploitable remotely over the network (CVSS attack vector: Network).

What is the CVSS score of CVE-2026-42578?

CVE-2026-42578 has a CVSS score of 7.5 (HIGH).

HOME VULNERABILITIESCVE-2026-42578

HIGH

CVE-2026-42578

CWE-113Published: May 13, 2026· Updated: May 18, 2026

7.5

CVSS v3.1

EPSS:0.05%probability of exploitation in 30 daysPercentile:14.7th

Official 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.

NVD Source

Technical Analysis

CVE-2026-42578 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A successful exploit results in full integrity compromise (data manipulation), with a CVSS base score of 7.5.