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.
References7
- github.com/netty/netty-tcnative
- github.com/netty/netty-tcnative/blob/netty-tcnative-parent-2.0.…
- github.com/netty/netty-tcnative/commit/a879c85b9776cf478aada3ca…
- github.com/netty/netty-tcnative/releases/tag/netty-tcnative-par…
- github.com/netty/netty-tcnative/security/advisories/GHSA-2784-h…
- www.vulncheck.com/advisories/netty-netty-tcnative-before-2.0.84…
- github.com/netty/netty-tcnative/security/advisories/GHSA-2784-h…
Metrics
- CVSS 3.1
-
5.3
MEDIUM
Score source: CNA
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N - CVSS 4.0
-
6.9
MEDIUM
Score source: CNA
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - EPSS — exploit probability
- 0% percentile: 11 · as of 8 November 2026
- CWE
- CWE-176
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.