CVE-2026-42580

Netty: HTTP Request Smuggling due to incorrect chunk size parsing

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.

Affected

netty · io.netty · netty-codec-http

CVSS v3.1 GITHUB

6.5 MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L

EPSS

0.36% chance of exploitation in the next 30 days, 29th percentile

Published

2026-05-13

Updated

2026-05-14

Proof-of-concept exploits (1)

• advisories/GHSA-m4cv-j2px-7723

Security advisories

• netty/netty/security/advisories/GHSA-m4cv-j2px-7723

References

• CVE Record
• NVD entry