CVE-2026-62243
Netty OpenSSL client can skip TLS hostname verification in certain Java/OpenSSL configs.
Is CVE-2026-62243 being exploited?
Not confirmed. CVE-2026-62243 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.15% probability of exploitation in the next 30 days.
How severe is CVE-2026-62243?
CVE-2026-62243 is rated High with a CVSS score of 8.7. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-62243?
Yes. A fix has been recorded for CVE-2026-62243. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-62243 affect?
CVE-2026-62243 affects io.netty:netty-handler 4.2.0.Final - 4.2.16.Final, io.netty:netty-handler <= 4.1.136.Final, SslProvider.OPENSSL client path, Java 25+ when Unsafe-based trust-manager wrapping unavailable. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-62243?
Upgrade to 4.2.17.Final or 4.1.137.Final and verify TLS hostname validation settings.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Man-in-the-middle attackers can present mismatched certificates; clients accept them, enabling interception and session hijack.
Patch when possible
- affected>= 4.2.0.Final and < 4.2.16.Final
- affected< 4.1.137.Final
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.