---
id: CVE-2026-116539
title: Netty netty-tcnative before 2.0.84.Final Heap Buffer Overflow via OpenSSL BIO
summary: >-
  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
  handshak…
severity: medium
cvss: 5.9
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H'
cvssSource: cna
cwe:
  - CWE-787
vendor: netty
product: 'io.netty:netty-tcnative'
affected:
  - 'io.netty:netty-tcnative < 2.0.84.Final'
  - 'io.netty:netty-tcnative-boringssl-static < 2.0.84.Final'
published: '2026-10-26'
updated: '2026-10-26'
sourceUpdated: '2026-10-26T14:59:39.460Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-116539'
references:
  - url: >-
      https://github.com/netty/netty-tcnative/security/advisories/GHSA-gf9q-9mg7-g5qh
    label: GitHub Security Advisory (GHSA-gf9q-9mg7-g5qh)
  - url: >-
      https://github.com/netty/netty-tcnative/commit/92dd66fd1243d85c05a61288f96367a70260b6b8
    label: Patch Commit
  - url: >-
      https://github.com/netty/netty-tcnative/blob/netty-tcnative-parent-2.0.83.Final/openssl-dynamic/src/main/c/ssl.c#L199
  - url: >-
      https://github.com/netty/netty-tcnative/releases/tag/netty-tcnative-parent-2.0.84.Final
    label: netty-tcnative netty-tcnative-parent-2.0.84.Final Release Notes
  - url: 'https://github.com/netty/netty-tcnative'
  - url: >-
      https://www.vulncheck.com/advisories/netty-netty-tcnative-before-2.0.84-final-heap-buffer-overflow-via-openssl-bio
    label: >-
      VulnCheck Advisory: Netty netty-tcnative before 2.0.84.Final Heap Buffer
      Overflow via OpenSSL BIO
tags:
  - cve.org
ingestedAt: '2026-10-26T15:29:30.504Z'
---

## Overview

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.

## Affected

- `io.netty:netty-tcnative < 2.0.84.Final`
- `io.netty:netty-tcnative-boringssl-static < 2.0.84.Final`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.