CVE-2026-62243: Software Security Vulnerability Vulnerability

HIGH
Advisory Identifier: GHSA-c3j3-64rf-grvf
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CVSS 7.5
CWE-297
Published
Advisory Summary

CVE-2026-62243 is a HIGH (CVSS 7.5) security vulnerability vulnerability (CWE-297: Improper Validation of Certificate with Host Mismatch) affecting Software libraries in the Maven ecosystem. The weakness occurs when the product communicates with a host that provides a certificate, but the product does not properly ensure that the certificate is actually associated with that host.. Remediation is available in the latest vendor maintenance releases.

CVE-2026-62243 at a Glance

CVE Identifier CVE-2026-62243
GHSA Identifier GHSA-c3j3-64rf-grvf
Severity HIGH
CVSS v3.1 Base Score 7.5
CWE Classification CWE-297: Improper Validation of Certificate with Host Mismatch
Affected Product Software
Package Ecosystem Maven
Published Date
Last Updated

Security Impact

CVSS: 7.5

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality High (C:H)
Integrity None (I:N)
Availability None (A:N)

How to Fix CVE-2026-62243

To remediate this vulnerability, upgrade all affected Software dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

mvn dependency:tree

How to Check if You Are Affected

To determine whether your Java application is affected by CVE-2026-62243, inspect your build dependencies using the Maven Dependency Plugin:

mvn dependency:tree

Analyze the terminal output to locate any version of Software in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than the patched release), your application is affected.

Note: The mvn dependency:tree command inspects the resolved dependency graph declared in your project's POM files; it does not perform automated security scanning or inspect runtime dynamic classpaths. Always verify runtime container classpaths and shaded JARs.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-297: Improper Validation of Certificate with Host Mismatch, where the product communicates with a host that provides a certificate, but the product does not properly ensure that the certificate is actually associated with that host. In Software, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

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.

References

GitHub Advisory / Wiki ADVISORY
https://github.com/netty/netty/security/advisories/GHSA-p85m-gvr3-788c
NVD — CVE-2026-62243 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-62243
www.vulncheck.com/advisories/netty-th... WEB
https://www.vulncheck.com/advisories/netty-through-tls-hostname-verification-bypass

Frequently Asked Questions

What is CVE-2026-62243?
CVE-2026-62243 is a security vulnerability in Software classified as a security vulnerability vulnerability under CWE-297: Improper Validation of Certificate with Host Mismatch.
Which Software versions are affected?
Affected versions include releases prior to current release patches.
What version fixes CVE-2026-62243?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
What is the CVSS score of CVE-2026-62243?
CVE-2026-62243 has a CVSS v3.1 base score of 7.5 (HIGH) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N.
What CWE is associated with CVE-2026-62243?
CVE-2026-62243 is classified under CWE-297: Improper Validation of Certificate with Host Mismatch (The product communicates with a host that provides a certificate, but the product does not properly ensure that the certificate is actually associated with that host.).
How can I check Maven dependencies for CVE-2026-62243?
Run the dependency tree command: 'mvn dependency:tree'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-c3j3-64rf-grvf",
  "modified" : "2026-08-22T15:31:02Z",
  "published" : "2026-08-22T15:31:02Z",
  "aliases" : [ "CVE-2026-62243" ],
  "details" : "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.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N"
  }, {
    "type" : "CVSS_V4",
    "score" : "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/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"
  } ],
  "affected" : [ ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/netty/netty/security/advisories/GHSA-p85m-gvr3-788c"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-62243"
  }, {
    "type" : "WEB",
    "url" : "https://www.vulncheck.com/advisories/netty-through-tls-hostname-verification-bypass"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-297" ],
    "severity" : "HIGH",
    "github_reviewed" : false,
    "github_reviewed_at" : null,
    "nvd_published_at" : "2026-08-22T13:16:39Z"
  }
}