How severe is CVE-2026-62243?

CVE-2026-62243 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.

Is CVE-2026-62243 being actively exploited?

It is not currently listed in CISA's Known Exploited Vulnerabilities catalog, and no EPSS exploit-prediction score is available yet.

How do I fix CVE-2026-62243?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2026-62243 published?

CVE-2026-62243 was published on 2026-08-22.

CVE-2026-62243

CVE-2026-62243 is a high-severity vulnerability with a CVSS 3.x base score of 7.5. The underlying weakness is classified as CWE-297.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v4: 8.7
Actively exploited: Not listed in CISA KEV
Weakness: CWE-297
Published: 2026-08-22
Last modified: 2026-08-22

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.

Frequently asked questions

What is CVE-2026-62243?: 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.
How severe is CVE-2026-62243?: CVE-2026-62243 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.
Is CVE-2026-62243 being actively exploited?: It is not currently listed in CISA's Known Exploited Vulnerabilities catalog, and no EPSS exploit-prediction score is available yet.
How do I fix CVE-2026-62243?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2026-62243 published?: CVE-2026-62243 was published on 2026-08-22.

References

Other CWE-297 vulnerabilities

CVE-2025-46408 — Critical (CVSS 9.8): An issue was discovered in the methods push.lite.avtech.com.AvtechLib.GetHttpsResponse and…
CVE-2026-59638 — Critical (CVSS 9.3): In Bouncy Castle for Java before 1.85, JSSE hostname verifier CN-fallback enabled by default despite documented opt-in.…
CVE-2026-15925 — Critical (CVSS 9.2): Improper TLS hostname verification in Snowflake Connector for Python versions prior to 4.7.1 and 3.18.1 may have…
CVE-2026-48144 — Critical (CVSS 9.1): Improper Validation of Certificate with Host Mismatch vulnerability in Apache Thrift c_glib bindings. This issue…
CVE-2025-68637 — Critical (CVSS 9.1): The Uniffle HTTP client is configured to trust all SSL certificates and disables hostname verification by default.…
CVE-2026-35563 — High (CVSS 8.5): It was identified that the LDAP client implementation in version 2.1.7 does not verify if the server certificate…

Browse all CWE-297 vulnerabilities →