---
id: "CVE-2026-116539"
kind: "vulnerability"
aliases: ["CVE-2026-116539"]
title: "Netty tcnative: remote TLS peer can crash JVM via heap overflow"
severity: "high"
cvss: 8.2
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["java", "jvm", "netty", "package", "tls"]
not_affected_if: ["jdk-tls-provider", "no-tcnative-dependency"]
published_at: "2026-10-26T16:17:19+00:00"
first_seen_at: "2026-10-26T16:31:01+00:00"
updated_at: "2026-10-26T16:32:47+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-116539", "first_seen_at": "2026-10-26T16:31:01+00:00"}]
---

# Netty tcnative: remote TLS peer can crash JVM via heap overflow

Netty's netty-tcnative library, before 2.0.84.Final, has a heap buffer overflow in its BIO write callback during TLS handshake, renegotiation, or post-handshake messages. A remote TLS peer can trigger an out-of-bounds memcpy that crashes the JVM process.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Check the netty-tcnative version in the project's dependency tree, for example with `mvn dependency:tree | grep tcnative` or `gradle dependencies | grep tcnative`
- Look for `netty-tcnative` or `netty-tcnative-boringssl-static` in the lock file or the packaged application

## Fix

- Upgrade netty-tcnative to `2.0.84.Final` or later
- Rebuild and redeploy the application so the new version ships in its artifact

## Timeline

- 2026-10-26T16:31:01+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-116539

## From the sources

Netty netty-tcnative before 2.0.84.Final contains a heap buffer overflow vulnerability in the tcn_write_to_bytebuffer BIO callback caused by failing to wrap the non-application ring buffer write index. Remote TLS peers can drive handshake, renegotiation, or post-handshake messages into this buffer, triggering an out-of-bounds memcpy that crashes the JVM process.

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