CVE-2026-62243
CVE-2026-62243 is a high-severity vulnerability with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-297.
Key facts
- Severity: High (CVSS 3.x base score 7.5)
- CVSS v4: 8.7
- EPSS exploit prediction: 0% (4th percentile)
- Actively exploited: Not listed in CISA KEV
- Weakness: CWE-297
- Published:
- Last modified:
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 KEV catalog. Its EPSS exploit-prediction score is 0% (4th percentile), an estimate of the probability of exploitation in the next 30 days.
- 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 and last updated on 2026-09-10.
References
- https://github.com/netty/netty/security/advisories/GHSA-p85m-gvr3-788c
- https://www.vulncheck.com/advisories/netty-through-tls-hostname-verification-bypass
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-2026-15925 — 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…
- CVE-2025-3501 — High (CVSS 8.2): A flaw was found in Keycloak. By setting a verification policy to 'ALL', the trust store certificate verification is…