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.
References7
- github.com/netty/netty-tcnative
- github.com/netty/netty-tcnative/blob/netty-tcnative-parent-2.0.…
- github.com/netty/netty-tcnative/commit/92dd66fd1243d85c05a61288…
- github.com/netty/netty-tcnative/releases/tag/netty-tcnative-par…
- github.com/netty/netty-tcnative/security/advisories/GHSA-gf9q-9…
- www.vulncheck.com/advisories/netty-netty-tcnative-before-2.0.84…
- github.com/netty/netty-tcnative/security/advisories/GHSA-gf9q-9…
Metrics
- CVSS 3.1
-
5.9
MEDIUM
Score source: CNA
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H - CVSS 4.0
-
8.2
HIGH
Score source: CNA
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/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: 34 · as of 8 November 2026
- CWE
- CWE-787
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.