Recently, NSFOCUS CERT detected that Oracle has released a security announcement, in which the remote code execution and denial of service vulnerabilities of Oracle WebLogic Server have been fixed. Affected users should take protective measures as soon as possible.
CVE-2025-21535: When the T3/IIOP protocol is enabled, an unauthenticated attacker sends a special request to the server through the T3/IIOP protocol to execute arbitrary code on the target system, resulting in remote takeover of the server. The CVSS score is 9.8.
CVE-2025-21549: Due to the design defect of HTTP/2 protocol, unauthenticated attackers can send special packets to WebLogic Server, causing server downtime or frequent crashes. The CVSS score is 7.5.
Reference link: https://www.oracle.com/security-alerts/cpujan2025.html
CVE-2025-21535:
CVE-2025-21549:
Note: The above is the influence scope that Oracle officially still supports maintenance at present, and multiple WebLogic Server versions such as 10.3.6.0, 11.1.1.9 and 12.1.3.0 have stopped maintenance.
Local detection
Users can run the following command to check the WebLogic version and patch installation.
$ cd /Oracle/Middleware/wlserver_10.3/server/lib
$ java -cp weblogic.jar weblogic.version
If no patch installation information is displayed in the output, a risk exists, as shown in the following figure.
T3 protocol detection
The Nmap tool provides a scanning script for the WebLogic T3 protocol to detect WebLogic hosts that enable the T3 service. The command is as follows:
As shown in the red box of the following figure, the target has enabled T3 protocol and WebLogic version is within the affected range. If relevant personnel do not install official security patches, there will be a vulnerability risk.
Patch update
At present, the Oracle database has released patches to fix the above vulnerabilities. Please refer to the official notice to download the update patch of the affected product in time, and install the update by referring to the readme file in the patch installation package to ensure long-term effective protection.
Note: The official patch of Oracle requires the user to have a license account of genuine software. After logging in https://support.oracle.com with this account, you can download the latest patch.
If users cannot install the update patch temporarily, you can take the following measures to temporarily protect high-risk vulnerabilities.
Restriction of T3 Protocol Access
Users can temporarily block attacks that exploit T3 protocol vulnerabilities by controlling access to the T3 protocol. WebLogic Server provides a default connection filter named weblogic.security.net.ConnectionFilterImpl, which accepts all incoming connections and can control access to T3 and T3s protocols through the configuration rules of this connection filter. The detailed operation steps are as follows:
1. Go to the WebLogic console. On the configuration page of base_domain, go to the “Security” tab page and click “Filters” to configure connection filters.
2. Enter weblogic.security.net.ConnectionFilterImpl in the connection filter, and configure rules conforming to actual situation of enterprise in the connection filter rule by referring to the following writing:
The connection filter rule format is as follows: target localAddress localPort action protocols, where:
3. If the rule does not take effect after saving, it is recommended to restart the WebLogic service (restarting the WebLogic service will cause business interruption. It is recommended that relevant personnel assess the risk before proceeding). Take the Windows environment as an example. The steps to restart the service are as follows:
Enter the bin directory under the directory where the domain is located, run stopWebLogic.cmd file in Windows system to terminate WebLogic service, and run stopWebLogic.sh file in Linux system.
After the termination script is executed, run the startWebLogic.cmd or startWebLogic.sh file to start WebLogic to restart the WebLogic service.
Disable IIOP Protocol
Users can block attacks that exploit IIOP protocol vulnerabilities by disabling the IIOP protocol. The operation is as follows: In the WebLogic console, choose Service -> AdminServer -> Protocol and unselect Enable IIOP. Restart the WebLogic project to make the configuration take effect.
This advisory is only used to describe a potential risk. NSFOCUS does not provide any commitment or promise on this advisory. NSFOCUS and the author will not bear any liability for any direct and/or indirect consequences and losses caused by transmitting and/or using this advisory. NSFOCUS reserves all the rights to modify and interpret this advisory. Please include this statement paragraph when reproducing or transferring this advisory. Do not modify this advisory, add/delete any information to/from it, or use this advisory for commercial purposes without permission from NSFOCUS.
NSFOCUS, a pioneering leader in cybersecurity, is dedicated to safeguarding telecommunications, Internet service providers, hosting providers, and enterprises from sophisticated cyberattacks.
Founded in 2000, NSFOCUS operates globally with over 4000 employees at two headquarters in Beijing, China, and Santa Clara, CA, USA, and over 50 offices worldwide. It has a proven track record of protecting over 25% of the Fortune Global 500 companies, including four of the five largest banks and six of the world’s top ten telecommunications companies.
Leveraging technical prowess and innovation, NSFOCUS delivers a comprehensive suite of security solutions, including the Intelligent Security Operations Platform (ISOP) for modern SOC, DDoS Protection, Continuous Threat Exposure Management (CTEM) Service and Web Application and API Protection (WAAP). All the solutions and services are augmented by the Security Large Language Model (SecLLM), ML, patented algorithms and other cutting-edge research achievements developed by NSFOCUS.
The post Oracle WebLogic Server Remote Code Execution and Denial of Service Vulnerability (CVE-2025-21535/CVE-2025-21549) appeared first on NSFOCUS, Inc., a global network and cyber security leader, protects enterprises and carriers from advanced cyber attacks..
*** This is a Security Bloggers Network syndicated blog from NSFOCUS, Inc., a global network and cyber security leader, protects enterprises and carriers from advanced cyber attacks. authored by NSFOCUS. Read the original post at: https://nsfocusglobal.com/oracle-weblogic-server-remote-code-execution-and-denial-of-service-vulnerability-cve-2025-21535-cve-2025-21549/