High 7.5Published May 13, 2026

CVE-2026-42582Netty: HTTP/3 QPACK literal unbounded allocation

Updated under an hour ago (Oct 27, 2026, 4:10 AM ET)

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No exploitation reported and no EPSS estimate yet.

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Exploited in the last 30 days

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.

CVSS: 7.5 HIGH (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness (CWE): CWE-770, CWE-789
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: GitHub_M
NVD analysis: Analyzed
Record last updated: May 13, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

netty netty netty:netty (from the name)	from 4.2.0.Alpha1, < 4.2.13.Final	CNA record
io.netty netty-codec-http3 io.netty:netty_codec_http3 (from the name)	from 4.2.0.Alpha1, < 4.2.13.Final	CNA record
netty netty netty:netty	from 4.2.0 before 4.2.13	NVD

References

References

https://github.com/netty/netty/security/advisories/GHSA-2c5c-chwr-9hqw	x-refsource-confirm, exploit, vendor-advisory

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.