CVE-2026-116542VulnerabilityPublished 26 Oct 2026Updated 28 Oct 2026

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

Affects netty-tcnativeSource GCVE Database

Authoritative record:CVE-2026-116542· Medium 6.9

Not known to be exploited · CVSS 6.9 Medium · fixed in 2.0.84 : update netty-tcnative when convenient.

Data as of 28 Oct 2026, 22:42 UTC

CVSS 4.0 base score

6.9Medium

How severe the flaw is on the 0–10 CVSS scale.

Patch: Available – fixed in 2.0.84

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

Attack Vector: Network
Attack Complexity: Low
Attack Requirements: None
Privileges Required: None
User Interaction: None
Vulnerable system confidentiality: None
Vulnerable system integrity: Low
Vulnerable system availability: None
Subsequent system confidentiality: None
Subsequent system integrity: None
Subsequent system availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Attack Requirements: None: The successful attack does not depend on the deployment and execution conditions of the vulnerable system. The attacker can expect to be able to reach the vulnerability and execute the exploit under all or most instances of the vulnerability.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without interaction from any human user, other than the attacker.
Vulnerable system confidentiality: None: There is no loss of confidentiality within the Vulnerable System.
Vulnerable system integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact to the Vulnerable System.
Vulnerable system availability: None: There is no impact to availability within the Vulnerable System.
Subsequent system confidentiality: None: There is no loss of confidentiality within the Subsequent System or all confidentiality impact is constrained to the Vulnerable System.
Subsequent system integrity: None: There is no loss of integrity within the Subsequent System or all integrity impact is constrained to the Vulnerable System.
Subsequent system availability: None: There is no impact to availability within the Subsequent System or all availability impact is constrained to the Vulnerable System.

Definitions: FIRST CVSS v4.0 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 26 Oct 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Patches and advisories

security-tracker.debian.org/tracker/cve-2026-116542 (opens in a new tab)

Affected software

Product	Affected	Fixed in
Ubuntu 26.10netty-tcnative`pkg:deb/ubuntu/netty-tcnative?arch=source&distro=stonking`Other threats	Affected =2.0.28-1build5 =2.0.28-1build6	Fixed in–
Ubuntu 26.04 LTSnetty-tcnative`pkg:deb/ubuntu/netty-tcnative?arch=source&distro=resolute`Other threats	Affected =2.0.28-1build4 =2.0.28-1build5	Fixed in–
Ubuntu 24.04 LTSnetty-tcnative`pkg:deb/ubuntu/netty-tcnative?arch=source&distro=noble`Other threats	Affected 2.0.28-1build1 – 2.0.28-1build4 4 affected builds	Fixed in–
Ubuntu 22.04 LTSnetty-tcnative`pkg:deb/ubuntu/netty-tcnative?arch=source&distro=jammy`Other threats	Affected =2.0.28-1 =2.0.28-1build1	Fixed in–
Ubuntu 20.04 LTSnetty-tcnative`pkg:deb/ubuntu/netty-tcnative?arch=source&distro=focal`Other threats	Affected =2.0.20-1 =2.0.28-1	Fixed in–
Ubuntu 18.04 LTSnetty-tcnative`pkg:deb/ubuntu/netty-tcnative?arch=source&distro=bionic`Other threats	Affected =1.1.33.Fork26-1 =1.1.33.Fork26-1build1	Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

A fix is available in netty-tcnative version 2.0.84.Final. Users should upgrade to this version or later to remediate the vulnerability. There are no indications that the vulnerability is mitigated by configuration or that no action is required.

Description

Netty netty-tcnative versions before 2.0.84.Final contain a Server Name Indication (SNI) hostname spoofing vulnerability. This flaw allows remote unauthenticated clients to manipulate hostnames via JNI NewStringUTF decoding by sending overlong encodings in the ClientHello server_name field. The vulnerability can cause confusion in SNI-based certificate selection, access control decisions, and logging, potentially leading to incorrect hostname handling.

Impact

The vulnerability allows remote unauthenticated attackers to spoof SNI hostnames, which may lead to incorrect certificate selection and access control decisions. This can undermine the security assumptions of TLS connections relying on SNI for hostname verification. However, the CVSS score of 5.3 (medium severity) indicates that the impact is limited to integrity and does not affect confidentiality or availability.

References

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