TI-2026-30862 Aliases CVE-2026-42582 GHSA-2c5c-chwr-9hqw

Netty: HTTP/3 QPACK literal unbounded allocation

HIGH 72CWE-770Published 2026-05-13 · Updated 2026-05-13

Key facts

Attack vector: Network
Privileges required: None
User interaction: None
Attack complexity: Low
Impact type: Denial of service
Confidentiality · integrity · availability: None · None · High
Fix status: Partial Red Hat: 1 without a fix

Attack profile from CVSS 3.1 · CNA. Fix status from CNA, GitHub and Red Hat. Impact type from CWE-770.

Summary

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.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV

EPSS 0.00437 38th percentileScored 2026-11-07

Public exploit Yes 1 exploit referenceTagged by NVD

Fix Partial netty (netty): 4.2.13.Finalnetty-codec-http3 (io.netty): 4.2.13.Final+1 more productRed Hat: 1 without a fix

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: Poc
Automatable: Yes
Technical impact: Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
netty	netty	4.2.0.Alpha1 to before 4.2.13.Final	4.2.13.Final	Patch available	CNA
netty	netty-codec-http3	4.2.0.Alpha1 to before 4.2.13.Final	4.2.13.Final	Patch available	CNA
—	io.netty:netty-codec-http3 (Maven)	4.2.0.Final to before 4.2.13.Final	4.2.13.Final	Patch available	GHSA-2c5c-chwr-9hqw

netty Vendornetty Affected 4.2.0.Alpha1 to before 4.2.13.Final Fixed in 4.2.13.Final Patch available CNA
netty-codec-http3 Vendornetty Affected 4.2.0.Alpha1 to before 4.2.13.Final Fixed in 4.2.13.Final Patch available CNA
io.netty:netty-codec-http3 (Maven) Vendor— Affected 4.2.0.Final to before 4.2.13.Final Fixed in 4.2.13.Final Patch available GHSA-2c5c-chwr-9hqw

CPE configurations NVD · 1

CPE	Versions	Role	Vendor
cpe:2.3:a:netty:netty::::::::	4.2.0 to before 4.2.13	Vulnerable	netty

cpe:2.3:a:netty:netty:*:*:*:*:*:*:*:* Versions 4.2.0 to before 4.2.13 Vulnerable ·netty

Remediation

Fix · CNA netty (netty) Fixed in 4.2.13.Final
Fix · CNA netty-codec-http3 (io.netty) Fixed in 4.2.13.Final
Fix · GHSA-2c5c-chwr-9hqw io.netty:netty-codec-http3 (Maven) Fixed in 4.2.13.Final Advisory →

Vendor assessments

Red Hat

Red Hat rating: Important. Red Hat's page for this CVE →

Product	Status	Plan or fix
Red Hat build of Apache Camel - HawtIO 4	Affected	No fix yet

Timeline

2026-10-02 Threatist record created from CVE-2026-42582
2026-10-03 Alias added: GHSA-2c5c-chwr-9hqw

References

TI-2023-23979 The HTTP/2 protocol allows a denial of service (server resource consumption) because… KEVCVSS 3.1HIGH 7.5
TI-2026-30861 Netty: HTTP/1.0 TE+CL Coexistence Bypasses Smuggling Sanitization CVSS 3.1CRITICAL 9.8
TI-2026-30864 Netty: HttpClientCodec response desynchronization CVSS 3.1CRITICAL 9.1
TI-2026-30859 Netty: DNS Codec Input Validation Bypass in Netty (Encoder + Decoder) CVSS 3.1CRITICAL 9.1
TI-2026-40973 Netty: Missing CertificateID Validation in OCSP Response Allows Replay Attacks CVSS 3.1CRITICAL 9.1
TI-2026-40972 Uncontrolled resource consumption in netty CVSS 3.1HIGH 7.5

See all 92 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences