Vulnerability · Published May 13, 2026 · Assigned by GitHub_M

CVE-2026-42577Netty: epoll transport denial of service via RST on half-closed TCP connection

High 7.5

In plain English

A high-severity security flaw in netty from netty. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 35% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)7.5High

Exploit odds (30 days)0.4%top 64.7% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

Netty is an asynchronous, event-driven network application framework. From 4.2.0.Final to 4.2.13.Final , Netty's epoll transport fails to detect and close TCP connections that receive a RST after being half-closed, leading to stale channels that are never cleaned up and, in some code paths, a 100% CPU busy-loop in the event loop thread. This vulnerability is fixed in 4.2.13.Final.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Debian:12	netty	no fix listed	DEBIAN-CVE-2026-42577
Debian:13	netty	no fix listed	DEBIAN-CVE-2026-42577
Debian:14	netty	no fix listed	DEBIAN-CVE-2026-42577
Maven	io.netty:netty-transport-classes-epoll	4.2.13.Final	GHSA-rwm7-x88c-3g2p
Ubuntu:25.10	netty	no fix listed	UBUNTU-CVE-2026-42577
Ubuntu:26.04:LTS	netty	no fix listed	UBUNTU-CVE-2026-42577

Affected products (as reported)

Vendor	Product	Versions
netty	netty	>= 4.2.0.Final, < 4.2.13.Final

Weakness: CWE-772 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References

https://github.com/netty/netty/security/advisories/GHSA-rwm7-x88c-3g2p x_refsource_CONFIRM
https://github.com/netty/netty/pull/16689 x_refsource_MISC
https://github.com/netty/netty/commit/0ec3d97fab376e243d328ac95fbd288ba0f6e22d x_refsource_MISC