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CVE-2026-42581 is an HTTP request-smuggling vulnerability in Netty's netty-codec-http component affecting releases before 4.1.133.Final in the 4.1.x branch and 4.2.13.Final in the 4.2.x branch. HttpObjectDecoder removes conflicting Content-Length headers from requests containing Transfer-Encoding: chunked only for HTTP/1.1 messages. For HTTP/1.0 requests, Netty decodes the body as chunked but retains Content-Length in the forwarded HttpMessage. Downstream proxies or handlers that prioritize Content-Length consequently interpret different message boundaries, enabling request smuggling.
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A request-smuggling vulnerability in Netty's HttpObjectDecoder. For HTTP/1.0 requests containing both Transfer-Encoding: chunked and Content-Length, Netty decodes the body as chunked but preserves Content-Length in the forwarded message. Downstream proxies or handlers that prioritize Content-Length can disagree with Netty about message boundaries, enabling request smuggling. The reference rates the vulnerability critical, with a CVSS v3 base score of 9.8.
A critical HTTP request-smuggling vulnerability in Netty caused by improper handling of conflicting HTTP/1.0 headers in Red Hat JBoss Enterprise Application Platform 7.1.z.
A Netty HTTP request-smuggling vulnerability caused by improper handling of conflicting HTTP/1.0 headers.
HTTP request-smuggling vulnerability in Netty caused by conflicting HTTP/1.0 header handling.
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