CVE-2026-34282 is a vulnerability in the networking component of Oracle Java SE, Oracle GraalVM for JDK, and Oracle GraalVM Enterprise Edition. It affects multiple specified versions including Oracle Java SE 8u481-perf, 11.0.30, 17.0.18, 21.0.10, 25.0.2, and 26, as well as GraalVM versions 17.0.18, 21.0.10, and Enterprise Edition 21.3.17. The flaw allows an unauthenticated attacker with network access to cause a hang or repeated crash, resulting in a complete denial of service. The vulnerability can be exploited via multiple protocols and through APIs, including web services that supply data to these APIs. It also affects sandboxed Java Web Start applications or applets that load untrusted code relying on the Java sandbox for security. The CVSS 3.1 vector indicates network attack vector, low attack complexity, no privileges required, no user interaction, unchanged scope, no confidentiality or integrity impact, and high availability impact (7.5). Oracle’s April 2026 Critical Patch Update advisory mentions this vulnerability but does not explicitly confirm patch availability or remediation level for the affected versions. No known exploits in the wild have been reported.

Successful exploitation results in an unauthorized ability to cause a hang or frequent crash of the affected Oracle Java SE and GraalVM products, leading to a complete denial of service (DoS). There is no impact on confidentiality or integrity. The vulnerability can be triggered remotely without authentication or user interaction, making it a significant availability risk for affected deployments.

Patch status is not yet confirmed — check the Oracle Critical Patch Update advisory at https://www.oracle.com/security-alerts/cpuapr2026.html for current remediation guidance. Oracle strongly recommends applying Critical Patch Updates promptly to mitigate vulnerabilities. Until a patch is confirmed and applied, consider restricting network access to affected services and monitoring for unusual application hangs or crashes related to Java networking components.