What’s Vulnerable › Vulnerabilities

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

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-05-13 · updated 2026-06-17
• Weakness: CWE-772

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 products

• netty: from 4.2.0 before 4.2.13 — fixed in 4.2.13

How to fix

Upgrade to a fixed version: netty 4.2.13. Check the vendor advisory for mitigations.

References

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

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