High severity · published Aug 22, 2026
CVE-2026-62243
Netty 4.2.0 through 4.2.16 TLS Hostname Verification Bypass
7.5
CVSS
0.2%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
High
Integrity
None
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.2% · higher than 5% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
NE
netty · netty
4.2.0.Final before 4.2.16.Final; before 4.1.137.Final · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-62243
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-62243
github.com
https://github.com/netty/netty/security/advisories/GHSA-p85m-gvr3-788c
www.vulncheck.com
https://www.vulncheck.com/advisories/netty-through-tls-hostname-verification-bypass
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