CVE-2023-21967 in Java SE
Summary
by MITRE • 04/18/2023
Vulnerability in the Oracle Java SE, Oracle GraalVM Enterprise Edition product of Oracle Java SE (component: JSSE). Supported versions that are affected are Oracle Java SE: 8u361, 8u361-perf, 11.0.18, 17.0.6, 20; Oracle GraalVM Enterprise Edition: 20.3.9, 21.3.5 and 22.3.1. Difficult to exploit vulnerability allows unauthenticated attacker with network access via HTTPS to compromise Oracle Java SE, 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 Enterprise Edition. Note: This vulnerability 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. This vulnerability can also be exploited by using APIs in the specified Component, e.g., through a web service which supplies data to the APIs. CVSS 3.1 Base Score 5.9 (Availability impacts). CVSS Vector: (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H).
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Analysis
by VulDB Data Team • 02/19/2025
This vulnerability resides within the Java Secure Socket Extension component of Oracle Java SE and GraalVM Enterprise Edition, representing a significant availability risk that can lead to complete denial of service conditions. The flaw manifests in the handling of certain SSL/TLS handshake sequences during HTTPS communications, creating a potential pathway for remote attackers to induce system instability. The vulnerability affects multiple major Java versions including 8u361, 11.0.18, 17.0.6, and 20, along with specific GraalVM Enterprise Edition releases 20.3.9, 21.3.5, and 22.3.1, indicating a broad impact across the Java ecosystem. According to CVSS 3.1 scoring, this vulnerability carries a base score of 5.9 with a high attack complexity and no required privileges, making it particularly dangerous in environments where Java applications process untrusted network data.
The technical exploitation of this vulnerability occurs through network-based attacks that leverage the Java sandbox mechanisms, specifically targeting the JSSE component's certificate validation and handshake processing. Attackers can trigger a denial of service condition by crafting specific SSL/TLS handshake messages that cause the Java runtime to enter an infinite loop or crash state. This behavior aligns with CWE-400 vulnerability classification related to resource exhaustion, where the system becomes unavailable due to improper handling of input data. The vulnerability's impact is particularly severe because it can be exploited without authentication and requires no user interaction, making it highly attractive to automated attack tools. The flaw essentially allows attackers to consume system resources or cause thread starvation in the SSL/TLS processing stack, resulting in complete system unavailability.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise entire application environments that rely on Java for secure communications. Systems running Java Web Start applications or applets that utilize HTTPS connections become particularly vulnerable, as these deployment models often execute untrusted code within sandboxed environments. The vulnerability's applicability to web services that utilize the affected APIs further amplifies its threat surface, as it could affect backend systems processing external SSL/TLS connections. Organizations using Oracle Java SE and GraalVM Enterprise Edition products in production environments face significant risk of service interruption, potentially affecting business continuity and customer access to critical applications. The vulnerability's classification under ATT&CK technique T1499.004 (Endpoint Denial of Service) highlights its potential for causing sustained availability issues that can persist until system restarts or patches are applied.
Mitigation strategies for this vulnerability should prioritize immediate patching of affected Java installations, with administrators focusing on upgrading to patched versions of Oracle Java SE and GraalVM Enterprise Edition. Organizations should implement network-level controls to restrict access to Java applications that process untrusted SSL/TLS data, particularly in environments where the vulnerability could be exploited through web services. Security monitoring should include detection of unusual SSL/TLS handshake patterns and resource consumption spikes that may indicate exploitation attempts. Additionally, organizations should consider disabling unnecessary HTTPS functionality in Java applications and implementing proper input validation for SSL/TLS related APIs. The vulnerability's characteristics make it particularly important for security teams to review their Java deployment configurations and ensure that sandboxed environments are properly isolated from critical system resources. Regular vulnerability assessments should be conducted to identify other potential attack vectors that could exploit similar weaknesses in Java security implementations.