Vulnerability · Published Oct 26, 2026 · Assigned by VulnCheck
CVE-2026-116539Netty netty-tcnative before 2.0.84.Final Heap Buffer Overflow via OpenSSL BIO
Medium 5.9
In plain English
A medium-severity out-of-bounds write in netty-tcnative from netty. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 34% of all known vulnerabilities).
Severity (CVSS 3.1)5.9Medium
Exploit odds (30 days)0.4%top 66.0% of all CVEs
Exploited in the wildNo reportsCISA SSVC: poc
Attack toolingNoneno public tooling known
Official description
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 packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | netty-tcnative | no fix listed | DEBIAN-CVE-2026-116539 |
| Debian:13 | netty-tcnative | no fix listed | DEBIAN-CVE-2026-116539 |
| Debian:14 | netty-tcnative | no fix listed | DEBIAN-CVE-2026-116539 |
| Ubuntu:22.04:LTS | netty-tcnative | no fix listed | UBUNTU-CVE-2026-116539 |
| Ubuntu:24.04:LTS | netty-tcnative | no fix listed | UBUNTU-CVE-2026-116539 |
| Ubuntu:26.04:LTS | netty-tcnative | no fix listed | UBUNTU-CVE-2026-116539 |
| Ubuntu:26.10 | netty-tcnative | no fix listed | UBUNTU-CVE-2026-116539 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| netty | netty-tcnative | 0 – before 2.0.84.Final |
| netty | netty-tcnative-boringssl-static | 0 – before 2.0.84.Final |
Weakness: CWE-787 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
References
- GitHub Security Advisory (GHSA-gf9q-9mg7-g5qh) vendor-advisory
- Patch Commit patch
- https://github.com/netty/netty-tcnative/blob/netty-tcnative-parent-2.0.83.Final/openssl-dynamic/src/main/c/ssl.c#L199 technical-description
- netty-tcnative netty-tcnative-parent-2.0.84.Final Release Notes release-notes
- https://github.com/netty/netty-tcnative product
- VulnCheck Advisory: Netty netty-tcnative before 2.0.84.Final Heap Buffer Overflow via OpenSSL BIO third-party-advisory