Vulnerability · Published Oct 26, 2026 · Assigned by VulnCheck
CVE-2026-116542Netty netty-tcnative before 2.0.84.Final SNI Hostname Spoofing via Modified UTF-8 Decoding
Medium 5.3
In plain English
A medium-severity security flaw 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 0.2% (higher than 11% of all known vulnerabilities).
Severity (CVSS 3.1)5.3Medium
Exploit odds (30 days)0.2%top 89.0% 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 an SNI hostname spoofing vulnerability that allows remote unauthenticated clients to alter hostnames via JNI NewStringUTF decoding. Attackers can send overlong encodings like 0xC0 0x80 in the ClientHello server_name to confuse SNI-based certificate selection, access decisions, and logging.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | netty-tcnative | no fix listed | DEBIAN-CVE-2026-116542 |
| Debian:13 | netty-tcnative | no fix listed | DEBIAN-CVE-2026-116542 |
| Debian:14 | netty-tcnative | no fix listed | DEBIAN-CVE-2026-116542 |
| Ubuntu:22.04:LTS | netty-tcnative | no fix listed | UBUNTU-CVE-2026-116542 |
| Ubuntu:24.04:LTS | netty-tcnative | no fix listed | UBUNTU-CVE-2026-116542 |
| Ubuntu:26.04:LTS | netty-tcnative | no fix listed | UBUNTU-CVE-2026-116542 |
| Ubuntu:26.10 | netty-tcnative | no fix listed | UBUNTU-CVE-2026-116542 |
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-176 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
References
- GitHub Security Advisory (GHSA-2784-hxmm-4hgf) vendor-advisory
- Patch Commit patch
- https://github.com/netty/netty-tcnative/blob/netty-tcnative-parent-2.0.83.Final/openssl-dynamic/src/main/c/sslcontext.c#L2608 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 SNI Hostname Spoofing via Modified UTF-8 Decoding third-party-advisory