CVE-2026-91411 in Java SE
Summary
by MITRE • 10/21/2026
Vulnerability in the Oracle Java SE, Oracle GraalVM for JDK, Oracle GraalVM Enterprise Edition product of Oracle Java SE (component: JGSS). Supported versions that are affected are Oracle Java SE: 8u503, 8u503-perf, 11.0.32.1; Oracle GraalVM for JDK: 17.0.20.1 and 21.0.12.1; Oracle GraalVM Enterprise Edition: 21.3.19.1.1. Difficult to exploit vulnerability allows unauthenticated attacker with network access via multiple protocols to compromise Oracle Java SE, Oracle GraalVM for JDK, Oracle GraalVM Enterprise Edition. Successful attacks of this vulnerability can result in unauthorized ability to cause a hang or frequently repeatable crash (complete DOS) of Oracle Java SE, Oracle GraalVM for JDK, Oracle GraalVM Enterprise Edition as well as unauthorized update, insert or delete access to some of Oracle Java SE, Oracle GraalVM for JDK, Oracle GraalVM Enterprise Edition accessible data. Note: This vulnerability can be exploited by using APIs in the specified Component, e.g., through a web service which supplies data to the APIs. This vulnerability also applies to Java deployments, typically in clients running sandboxed Java Web Start applications or sandboxed Java applets, that load and run untrusted code (e.g., code that comes from the internet) and rely on the Java sandbox for security. CVSS 3.1 Base Score 6.5 (Integrity and Availability impacts). CVSS Vector: (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H).
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Analysis
by VulDB Data Team • 10/21/2026
The identified vulnerability resides within the Java GSS-API, commonly referred to as JGSS, a core component of Oracle Java SE and related GraalVM distributions responsible for handling security context establishment and token exchange in networked applications. This flaw affects specific supported versions including Oracle Java SE 8u503 and 11.0.32.1, alongside corresponding releases of Oracle GraalVM for JDK and Enterprise Edition. The technical nature of the defect allows an unauthenticated attacker to exploit the vulnerability over multiple network protocols without requiring user interaction or prior authentication credentials. This characteristic significantly lowers the barrier for exploitation compared to vulnerabilities that require complex social engineering or specific application states, enabling remote attackers to target systems directly through standard network interfaces such as HTTP, HTTPS, or other JGSS-supported transport mechanisms.
The operational impact of this vulnerability is twofold, affecting both system availability and data integrity. On one hand, the flaw can be leveraged to cause a hang or induce frequent, repeatable crashes within the Java runtime environment, resulting in a complete denial of service condition for applications relying on JGSS functionality. This disruption prevents legitimate users from accessing services hosted by vulnerable systems. On the other hand, successful exploitation grants unauthorized actors the ability to perform update, insert, or delete operations against accessible data managed by the affected components. This compromise of integrity means that sensitive information can be altered, corrupted, or removed without authorization, potentially leading to significant business disruption and loss of trust in the application's reliability and security posture.
This vulnerability is particularly relevant for Java deployments where untrusted code is executed within a sandboxed environment, such as Java Web Start applications or applets loaded from the internet. These environments typically rely on the Java sandbox model to restrict access to system resources and enforce security policies. However, flaws in foundational components like JGSS can undermine these protections if the vulnerability allows escape from expected constraints or manipulation of underlying data structures before proper validation occurs. Attackers may exploit APIs within this component by supplying maliciously crafted data through web services or other networked interfaces that feed into the Java runtime, effectively bypassing standard security expectations for untrusted inputs in sandboxed contexts.
From a classification perspective, this issue aligns with CWE-20 Improper Input Validation and CWE-436 Interpretation Conflict if the root cause involves ambiguous parsing of GSS-API tokens or context data. The attack vector corresponds to MITRE ATT&CK technique T1190 Exploit Public-Facing Application, as it targets a component accessible via network protocols without authentication. Additionally, the ability to crash services maps to availability impacts often associated with resource exhaustion or logic errors in handling malformed inputs. Security professionals should prioritize patching affected versions immediately, ensuring that Oracle Java SE and GraalVM updates are applied according to vendor guidelines. Furthermore, organizations should review their JGSS configurations for any unnecessary exposure of network ports and implement strict input validation at the application layer as a defense-in-depth measure while awaiting full remediation through official patches.