Netty (io.netty:netty-handler) versions from 4.2.0.Final through 4.2.16.Final and versions through 4.1.136.Final disable TLS hostname verification on the SslProvider.OPENSSL client path when a plain (non-extended) X509TrustManager is used and Unsafe-based trust-manager wrapping is unavailable (Java 25+). In this configuration the OpenSSL client does not perform hostname verification, allowing a man-in-the-middle attacker to present a certificate issued for a different hostname that is accepted without validation. Fixed in 4.2.17.Final and 4.1.137.Final.

Metrics

Attack Vector Network

Attack Complexity Low

Privileges Required None

Attack Requirements None

User Interaction None

Vulnerable System Confidentiality Impact High

Vulnerable System Integrity Impact None

Vulnerable System Availability Impact None

Subsequent System Confidentiality Impact None

Subsequent System Integrity Impact None

Subsequent System Availability Impact None

Attack Vector Network

Attack Complexity Low

Privileges Required None

Scope Unchanged

Confidentiality Impact High

Integrity Impact None

Availability Impact None

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

Exploitation none

Automatable yes

Technical Impact partial

Affected Vendors & Products

Vendors Products
Netty
  • Netty

No data.

No data.

References
Link Providers
https://github.com/netty/netty/security/advisories/GHSA-p85m-gvr3-788c cve-icon cve-icon cve-icon
https://nvd.nist.gov/vuln/detail/CVE-2026-62243 cve-icon
https://www.cve.org/CVERecord?id=CVE-2026-62243 cve-icon
https://www.vulncheck.com/advisories/netty-through-tls-hostname-verification-bypass cve-icon cve-icon cve-icon
History

Mon, 31 Aug 2026 12:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-295
References
Metrics threat_severity

None

 threat_severity

Important

Mon, 24 Aug 2026 20:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Sat, 22 Aug 2026 12:45:00 +0000

Type Values Removed Values Added
Description Netty (io.netty:netty-handler) versions from 4.2.0.Final through 4.2.16.Final and versions through 4.1.136.Final disable TLS hostname verification on the SslProvider.OPENSSL client path when a plain (non-extended) X509TrustManager is used and Unsafe-based trust-manager wrapping is unavailable (Java 25+). In this configuration the OpenSSL client does not perform hostname verification, allowing a man-in-the-middle attacker to present a certificate issued for a different hostname that is accepted without validation. Fixed in 4.2.17.Final and 4.1.137.Final.
Title Netty 4.2.0 through 4.2.16 TLS Hostname Verification Bypass
First Time appeared Netty
Netty netty
Weaknesses CWE-297
CPEs cpe:2.3:a:netty:netty:*:*:*:*:*:*:*:*
Vendors & Products Netty
Netty netty
References
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N'}

cvssV4_0

{'score': 8.7, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N'}
cve-icon MITRE

Status: PUBLISHED

Assigner: VulnCheck

Published: 2026-08-22T12:26:43.072Z

Updated: 2026-08-24T19:36:53.644Z

Reserved: 2026-07-13T16:41:09.007Z

Link: CVE-2026-62243

cve-icon Vulnrichment

Updated: 2026-08-24T19:36:48.745Z

cve-icon NVD

Status : Received

Published: 2026-08-22T13:16:39.687

Modified: 2026-08-24T20:16:52.993

Link: CVE-2026-62243

cve-icon Redhat

Severity : Important

Publid Date: 2026-08-22T12:26:43Z

Links: CVE-2026-62243 - Bugzilla