Medium 6.5Published May 13, 2026

CVE-2026-42580Netty: HTTP Request Smuggling due to incorrect chunk size parsing

Updated under an hour ago (Oct 26, 2026, 2:30 PM 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 and 4.1.133.Final, Netty's chunk size parser silently overflows int, enabling request smuggling attacks. This vulnerability is fixed in 4.2.13.Final and 4.1.133.Final.

CVSS: 6.5 MEDIUM (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L
Weakness (CWE): CWE-444, CWE-190
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 14, 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; before 4.1.133.Final	CNA record
io.netty netty-codec-http io.netty:netty_codec_http (from the name)	from 4.2.0.Alpha1, < 4.2.13.Final; before 4.1.133.Final	CNA record
netty netty netty:netty	before 4.1.133; from 4.2.0 before 4.2.13	NVD

References

References

https://github.com/netty/netty/security/advisories/GHSA-m4cv-j2px-7723	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.