What’s Vulnerable › Vulnerabilities

CVE-2026-116542: Netty netty-tcnative before 2.0.84.Final SNI Hostname Spoofing via Modified UTF-8 Decoding

• Severity: medium (CVSS 5.3 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-10-26 · updated 2026-10-31
• Weakness: CWE-176

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 products

• netty-tcnative: before 2.0.84.Final — fixed in 2.0.84.Final
• netty-tcnative-boringssl-static: before 2.0.84.Final — fixed in 2.0.84.Final

How to fix

Upgrade to a fixed version: netty-tcnative 2.0.84.Final; netty-tcnative-boringssl-static 2.0.84.Final. Check the vendor advisory for mitigations.

References

• https://github.com/netty/netty-tcnative
• https://github.com/netty/netty-tcnative/blob/netty-tcnative-parent-2.0.83.Final/openssl-dynamic/src/main/c/sslcontext.c#L2608
• https://github.com/netty/netty-tcnative/commit/a879c85b9776cf478aada3ca69e60b8c0a99ed38
• https://github.com/netty/netty-tcnative/releases/tag/netty-tcnative-parent-2.0.84.Final
• https://github.com/netty/netty-tcnative/security/advisories/GHSA-2784-hxmm-4hgf
• https://www.vulncheck.com/advisories/netty-netty-tcnative-before-2.0.84-final-sni-hostname-spoofing-via-modified-utf-8-decoding
• https://github.com/netty/netty-tcnative/security/advisories/GHSA-2784-hxmm-4hgf

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