CVE-2026-42582

Netty: HTTP/3 QPACK literal unbounded allocation

State: Published
Severity: 7.5 High
Published: May 13, 2026
Updated: May 13, 2026
Reserved: Apr 28, 2026

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.

Scores

CVSS	Score	Vector	Source
3.1	7.5 High	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H	GitHub_M

Weaknesses

CWE-770 Allocation of Resources Without Limits or Throttling
CWE-789 Memory Allocation with Excessive Size Value

Affected Products

Product	Versions
nettynetty	>= 4.2.0.Alpha1, < 4.2.13.FinalAffected
netty-codec-http3io.netty	>= 4.2.0.Alpha1, < 4.2.13.FinalAffected

References

https://github.com/netty/netty/security/advisories/GHSA-2c5c-chwr-9hqw

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