CVE-2025-21549 Overview
CVE-2025-21549 is a Denial of Service vulnerability in the Oracle WebLogic Server product of Oracle Fusion Middleware, specifically affecting the Core component. This easily exploitable vulnerability allows an unauthenticated attacker with network access via HTTP/2 to compromise Oracle WebLogic Server, resulting in a complete hang or frequently repeatable crash of the affected system.
Critical Impact
Unauthenticated remote attackers can cause complete service disruption of Oracle WebLogic Server through HTTP/2 requests, leading to total availability impact with no authentication required.
Affected Products
- Oracle WebLogic Server version 14.1.1.0.0
- Oracle Fusion Middleware (Core component)
- Systems exposing HTTP/2 protocol endpoints
Discovery Timeline
- 2025-01-21 - CVE-2025-21549 published to NVD
- 2025-06-23 - Last updated in NVD database
Technical Details for CVE-2025-21549
Vulnerability Analysis
This vulnerability resides in the Core component of Oracle WebLogic Server and is classified as CWE-400 (Uncontrolled Resource Consumption). The flaw allows attackers to trigger resource exhaustion conditions that lead to a complete denial of service. The attack can be executed remotely over the network without requiring any authentication or user interaction, making it particularly dangerous for internet-facing WebLogic deployments.
The vulnerability specifically affects HTTP/2 protocol handling within WebLogic Server. When exploited, attackers can cause the server to enter a hung state or trigger repeated crashes, effectively rendering the application server unavailable to legitimate users. Given that WebLogic Server is commonly used for mission-critical enterprise applications, the impact of successful exploitation can be severe for business operations.
Root Cause
The vulnerability stems from improper handling of HTTP/2 protocol requests in the WebLogic Server Core component, leading to uncontrolled resource consumption (CWE-400). The server fails to properly validate or limit certain HTTP/2 request parameters, allowing malicious actors to consume excessive system resources and trigger denial of service conditions.
Attack Vector
The attack is executed via network access using the HTTP/2 protocol. An unauthenticated attacker can craft malicious HTTP/2 requests targeting vulnerable WebLogic Server instances. The attack requires no privileges, no user interaction, and can be launched remotely against any exposed HTTP/2 endpoint. The low attack complexity means exploitation can be automated and scaled against multiple targets.
The vulnerability manifests when malformed or specially crafted HTTP/2 requests are processed by the WebLogic Server Core component. See the Oracle Security Alert January 2025 for complete technical details and patch information.
Detection Methods for CVE-2025-21549
Indicators of Compromise
- Unexpected WebLogic Server process crashes or hang conditions
- Elevated resource consumption (CPU, memory) on WebLogic Server hosts without corresponding legitimate traffic increases
- Unusual HTTP/2 request patterns or malformed protocol data in access logs
- Service availability alerts for WebLogic-hosted applications
Detection Strategies
- Monitor WebLogic Server process health and implement automated restart policies to detect repeated crash conditions
- Implement network-level monitoring for anomalous HTTP/2 traffic patterns targeting WebLogic endpoints
- Deploy application performance monitoring (APM) to detect resource exhaustion events
- Enable WebLogic Server diagnostic logging for Core component errors
Monitoring Recommendations
- Configure alerts for WebLogic Server availability metrics and unexpected service restarts
- Implement rate limiting and connection throttling for HTTP/2 endpoints at the network perimeter
- Monitor server resource utilization metrics including memory, CPU, and thread pool exhaustion
- Review WebLogic Server logs for HTTP/2 protocol processing errors
How to Mitigate CVE-2025-21549
Immediate Actions Required
- Apply the security patch from Oracle's January 2025 Critical Patch Update immediately
- If immediate patching is not possible, consider temporarily disabling HTTP/2 protocol support on affected WebLogic Server instances
- Implement network-level access controls to restrict HTTP/2 access to trusted sources only
- Enable enhanced monitoring for WebLogic Server availability and resource consumption
Patch Information
Oracle has released a security patch addressing this vulnerability as part of the January 2025 Critical Patch Update. Administrators should consult the Oracle Security Alert January 2025 for detailed patch installation instructions and affected version information. The patch should be applied to all Oracle WebLogic Server 14.1.1.0.0 installations as soon as possible.
Workarounds
- Disable HTTP/2 protocol support on WebLogic Server if not required for business operations
- Implement Web Application Firewall (WAF) rules to filter potentially malicious HTTP/2 requests
- Deploy network segmentation to limit exposure of WebLogic Server instances to untrusted networks
- Configure load balancers to perform HTTP/2 protocol termination and request validation before forwarding to WebLogic
# Example: Restrict access to WebLogic HTTP/2 endpoints using iptables
# Limit connections to trusted networks only until patching is complete
iptables -A INPUT -p tcp --dport 7001 -s 10.0.0.0/8 -j ACCEPT
iptables -A INPUT -p tcp --dport 7001 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
