CVE-2026-42582

High

Description

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.

SeverityHigh

CVSS7.5

Exploit probability—

ProductNetty

PublishedMay 13, 2026

First seenMay 13, 2026

Weakness typeCWE-770Allocation of resources without limits CWE-789CWE-789

How to fix

Update

netty netty4.2.13 or later
io.netty:netty-codec-http34.2.13.Final or later

Affected products

Product	Affected versions	Fixed in
netty netty	4.2.0 ≤ v < 4.2.13	4.2.13
io.netty:netty-codec-http3Maven	4.2.0.Final ≤ v < 4.2.13.Final	4.2.13.Final

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