CVE-2026-61308 Overview
CVE-2026-61308 affects the Networking component of Oracle Java SE, Oracle GraalVM for JDK, and Oracle GraalVM Enterprise Edition. An unauthenticated attacker with network access via HTTP can compromise affected installations. The vulnerability requires high attack complexity but produces a scope change, meaning successful exploitation impacts components beyond the vulnerable Java runtime. Successful attacks result in unauthorized access to critical data or complete access to all data accessible to Oracle Java SE, Oracle GraalVM for JDK, and Oracle GraalVM Enterprise Edition.
Critical Impact
Unauthenticated network attackers can obtain unauthorized read access to sensitive data across Java deployments, with scope change amplifying impact to adjacent components.
Affected Products
- Oracle Java SE versions 8u501, 11.0.32, 17.0.20, 21.0.12, 25.0.4, 26.0.2
- Oracle GraalVM for JDK versions 17.0.20 and 21.0.12
- Oracle GraalVM Enterprise Edition version 21.3.19
Discovery Timeline
- 2026-08-18 - CVE-2026-61308 published to NVD
- 2026-08-20 - Last updated in NVD database
Technical Details for CVE-2026-61308
Vulnerability Analysis
The vulnerability resides in the Networking component of the affected Java runtimes. Attackers exploit the flaw by supplying crafted data to APIs in the Networking component, typically through a web service that forwards data to those APIs. The scope change indicates the vulnerable component can influence resources managed by a different security authority, extending impact beyond the Java runtime process itself.
Oracle documents the issue as an Information Disclosure weakness affecting confidentiality only. Integrity and availability remain unaffected, but the attacker can retrieve all data accessible to the Java process. EPSS data lists the exploit probability at 0.318% with a percentile of 24.752.
Root Cause
Oracle has not released public root-cause details beyond the advisory. The flaw is located in networking APIs that process attacker-controlled input, likely during HTTP request handling or URL parsing. Because the runtime enforces a security scope, the defect enables cross-scope disclosure when untrusted code interacts with the affected APIs.
Attack Vector
The vulnerability is exploitable remotely over HTTP without authentication. Two exploitation paths apply. Server-side attackers submit malicious input through any web service that forwards data to the Networking APIs. Client-side attackers deliver sandboxed Java Web Start applications or sandboxed Java applets that load untrusted code and rely on the Java sandbox for security containment.
Exploitation code is not publicly available. Refer to the Oracle Security Alert for vendor-supplied technical details.
Detection Methods for CVE-2026-61308
Indicators of Compromise
- Anomalous outbound HTTP connections initiated by Java processes to attacker-controlled hosts.
- Unexpected reads of configuration, credential, or certificate files by java or graalvm processes.
- Java Web Start (javaws) or applet execution originating from untrusted network locations.
Detection Strategies
- Inventory endpoints and servers running the affected Java SE, GraalVM for JDK, and GraalVM Enterprise Edition versions using software asset management data.
- Inspect HTTP request logs at web services fronting Java APIs for malformed URIs, oversized headers, or unusual protocol constructs targeting the Networking component.
- Correlate outbound network telemetry from JVM processes with sensitive file access events to identify possible data staging.
Monitoring Recommendations
- Alert on Java processes issuing HTTP requests to previously unseen external hosts, especially shortly after handling inbound traffic.
- Monitor Java Web Start and applet execution events on user endpoints and treat sandboxed loads from the internet as high-risk.
- Track process command lines for -Djava.net.* overrides that could disable networking safeguards.
How to Mitigate CVE-2026-61308
Immediate Actions Required
- Apply the Oracle Critical Patch Update referenced in the Oracle Security Alert to all affected Java SE and GraalVM installations.
- Disable Java Web Start and browser applet execution on endpoints that do not require them.
- Restrict which internal web services can forward untrusted input to Java Networking APIs.
Patch Information
Oracle addressed CVE-2026-61308 in the August 2026 Critical Patch Update. Upgrade to the fixed releases published by Oracle for Java SE, GraalVM for JDK, and GraalVM Enterprise Edition. Consult the Oracle Security Alert for the exact fixed versions and download locations.
Workarounds
- Enforce egress filtering on servers running affected Java runtimes to limit destinations reachable by JVM processes.
- Remove or restrict the Java plugin and Web Start on user workstations to eliminate the sandboxed-applet exploitation path.
- Front Java web services with an application-layer gateway that validates and normalizes HTTP inputs before they reach Java Networking APIs.
# Verify installed Java version and remove legacy runtimes on Linux
java -version
rpm -qa | grep -Ei 'jdk|graalvm'
sudo yum remove jdk-17.0.20 graalvm-jdk-21.0.12
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
