Netty 4.2.0 through 4.2.16 TLS Hostname Verification Bypass (CVE-2026-62243) | HOL Guard CVE

Unknown severity · Source severity not reportedCVE-2026-62243

Netty 4.2.0 through 4.2.16 TLS Hostname Verification Bypass

Answer in brief

CVE-2026-62243 records a Unknown severity vulnerability in Netty 4.2.0 through 4.2.16 TLS Hostname Verification Bypass. The current sources do not mark it as known exploited. The current feed maps netty/netty (generic), netty/netty (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Aug 22, 2026Updated Aug 22, 2026Source checked Aug 22, 2026First seen by HOL Aug 22, 2026Material review Aug 22, 2026

Upstream Advisory

Key facts

Risk: Unknown severitySource severity not reported
Exploitation: Not marked as known exploited
Affected software: 2 mapped packages or products
Fix availability: Available

Why this deserves its current priority

A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps netty/netty (generic), netty/netty (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
netty/nettygeneric	>=4.2.0.Final <4.2.16.Final	4.2.16.Final
netty/nettygeneric	>=0 <4.1.137.Final	4.1.137.Final

Recommended response

Check inventory. Check lockfiles and deployed manifests for netty/netty, netty/netty.
Review the reported fix. Update netty/netty to 4.2.16.Final; netty/netty to 4.1.137.Final if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Aug 22, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Aug 22, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Aug 22, 2026

Sources and claim methodology

Upstream source 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.

Quoted source text, attributed separately from HOL analysis.