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CVE-2026-116542

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

6.9 MediumFix available

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.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
None
Integrity
Low
Availability
None

Exploit likelihood

0.21%Unchanged since Oct 27, 2026
90%50%10%1%

What each source reports

CVE List Score used 6.9

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

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.

Record
CVE-2026-116542
CVSS 4.0
6.9 MediumCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
CVSS 3.1
5.3 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Weakness
CWE-176
Updated
2026-11-02
EUVDEUVD-2026-109912 6.9

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.

Record
EUVD-2026-109912
CVSS 4.0
6.9 MediumCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
Updated
2026-11-02
GitHub AdvisoriesGHSA-98m4-7wj9-fxmw 6.9

Netty netty-tcnative before 2.0.84.Final contains an SNI hostname spoofing vulnerability that...

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.

Record
GHSA-98m4-7wj9-fxmw
CVSS 4.0
6.9 MediumCVSS: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
CVSS 3.1
5.3 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Weakness
CWE-176
Updated
2026-11-02
NVD 6.9

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.

Record
CVE-2026-116542
CVSS 4.0
6.9 MediumCVSS: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
CVSS 3.1
5.3 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Weakness
CWE-176
Updated
2026-11-02
OSV 6.9

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

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.

Record
CVE-2026-116542
CVSS 4.0
6.9 MediumCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
Weakness
CWE-176
Updated
2026-11-04
OSVDEBIAN-CVE-2026-116542 6.9

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.

Record
DEBIAN-CVE-2026-116542
CVSS 4.0
6.9 MediumCVSS: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
Updated
2026-11-02
OSVUBUNTU-CVE-2026-116542 6.9

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.

Record
UBUNTU-CVE-2026-116542
CVSS 4.0
6.9 MediumCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
CVSS 3.1
5.3 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Updated
2026-11-02
OSVopenSUSE-SU-2026:12403-1 No score

netty-tcnative-2.0.85-1.1 on GA media

These are all security issues fixed in the netty-tcnative-2.0.85-1.1 package on the GA media of openSUSE Tumbleweed.

Record
openSUSE-SU-2026:12403-1
Updated
2026-11-04

Affected products

Affected packages

Affected packages
PackageAffectedFixed
netty-tcnative
Debian:12
 All versions, plus listed versions
2.0.28-1
 None known
netty-tcnative
Debian:13
 All versions, plus listed versions
2.0.28-1
 None known
netty-tcnative
Debian:14
 All versions, plus listed versions
2.0.28-1
 None known
netty-tcnative
Ubuntu:16.04:LTS
 All versions, plus listed versions
1.1.33.Fork6-11.1.33.Fork10-21.1.33.Fork14-1
 None known
netty-tcnative
Ubuntu:18.04:LTS
 All versions, plus listed versions
1.1.33.Fork26-11.1.33.Fork26-1build1
 None known
netty-tcnative
Ubuntu:20.04:LTS
 All versions, plus listed versions
2.0.20-12.0.28-1
 None known
netty-tcnative
Ubuntu:22.04:LTS
 All versions, plus listed versions
2.0.28-12.0.28-1build1
 None known
netty-tcnative
Ubuntu:24.04:LTS
 All versions, plus listed versions
2.0.28-1build12.0.28-1build22.0.28-1build32.0.28-1build4
 None known
netty-tcnative
Ubuntu:26.10
 All versions, plus listed versions
2.0.28-1build52.0.28-1build6
 None known
netty-tcnative
Ubuntu:26.04:LTS
 All versions, plus listed versions
2.0.28-1build42.0.28-1build5
 None known
netty-tcnative
openSUSE:Tumbleweed
 before 2.0.85-1.1
2.0.85-1.1

History

History
RecordedChangedSources
affected, aliases, facts, referencesOSV
first indexedCVE List, EUVD, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-116542 is a medium vulnerability (CVSS 6.9) in Netty Netty-tcnative, published October 26, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.21%, the 11th percentile. Fixed in netty-tcnative 2.0.85-1.1.

References

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