Bug 2477221 (CVE-2026-42582)

Summary: CVE-2026-42582 netty: io.netty/netty-codec-http3: Netty: Denial of Service due to improper length validation in header block decoding
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: high Docs Contact:
Priority: high    
Version: unspecifiedCC: abrianik, ggrzybek, jraez, parichar, tasato
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in Netty, an asynchronous, event-driven network application framework. A remote attacker could exploit this vulnerability by sending a specially crafted compressed field section during header block decoding. This flaw occurs because the system allocates a new byte array based on a provided length without verifying if enough bytes are present in the compressed data. This can lead to excessive memory allocation, resulting in a Denial of Service (DoS) for the affected system.
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Description OSIDB Bzimport 2026-05-13 19:02:01 UTC 
Netty is an asynchronous, event-driven network application framework. Prior to 4.2.13.Final, when decoding header blocks, the non-Huffman branch of io.netty.handler.codec.http3.QpackDecoder#decodeHuffmanEncodedLiteral may execute new byte[length] for a string literal before verifying that length bytes are actually present in the compressed field section. The wire encoding allows a very large length to be expressed in few bytes. There is no check that length <= in.readableBytes() before new byte[length]. This vulnerability is fixed in 4.2.13.Final.