Vulnerability Details CVE-2026-42582
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.
Exploit prediction scoring system (EPSS) score
EPSS Score 0.004
EPSS Ranking 36.4%
CVSS Severity
CVSS v3 Score 7.5
References
Products affected by CVE-2026-42582
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cpe:2.3:a:netty:netty:4.2.0
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cpe:2.3:a:netty:netty:4.2.1
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cpe:2.3:a:netty:netty:4.2.10
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cpe:2.3:a:netty:netty:4.2.11
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cpe:2.3:a:netty:netty:4.2.12
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cpe:2.3:a:netty:netty:4.2.2
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cpe:2.3:a:netty:netty:4.2.3
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cpe:2.3:a:netty:netty:4.2.4
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cpe:2.3:a:netty:netty:4.2.5
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cpe:2.3:a:netty:netty:4.2.6
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cpe:2.3:a:netty:netty:4.2.7
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cpe:2.3:a:netty:netty:4.2.8
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cpe:2.3:a:netty:netty:4.2.9