CVE-2026-42582

Netty: HTTP/3 QPACK literal unbounded allocation

Published May 13, 2026 CVSS 3.1 · 7.5 High EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Github GHSA Github GHSA GHSA-2c5c-chwr-9hqw Netty HTTP/3 QPACK literal unbounded allocation
History
Type Values Removed Values Added
CPEs cpe:2.3:a:netty:netty:*:*:*:*:*:*:*:*
Type Values Removed Values Added
First Time appeared Io.netty
Io.netty netty-codec-http3
Netty
Netty netty
Vendors & Products Io.netty
Io.netty netty-codec-http3
Netty
Netty netty
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
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.
Title Netty: HTTP/3 QPACK literal unbounded allocation
Weaknesses CWE-770
CWE-789
References
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
May 13, 2026, 7:35 PM
Reserved
Apr 28, 2026, 5:26 PM
Status
Analyzed
Published
May 13, 2026, 7:17 PM
Modified
Oct 26, 2026, 12:10 AM