CVE-2024-1300 Overview
A memory leak vulnerability exists in the Eclipse Vert.x toolkit affecting TCP servers configured with TLS and Server Name Indication (SNI) support. When the server processes an unknown SNI server name and assigns the default certificate instead of a mapped certificate, the SSL context is erroneously cached in the server name map. This improper memory management leads to memory exhaustion over time, allowing attackers to trigger a JVM out-of-memory error by sending specially crafted TLS client hello messages with fake server names.
Critical Impact
Attackers can exhaust server memory by sending repeated TLS client hello messages with fake SNI server names, leading to denial of service through JVM out-of-memory conditions.
Affected Products
- Eclipse Vert.x toolkit (versions with TLS and SNI support enabled)
- Red Hat products utilizing affected Vert.x versions (see Red Hat Security Advisories)
- Java applications using Vert.x Core with SNI-enabled TCP servers
Discovery Timeline
- 2024-04-02 - CVE-2024-1300 published to NVD
- 2024-11-25 - Last updated in NVD database
Technical Details for CVE-2024-1300
Vulnerability Analysis
This vulnerability is classified under CWE-401 (Missing Release of Memory after Effective Lifetime), representing a classic memory leak pattern in the Vert.x networking stack. The flaw resides in the TLS/SNI handling mechanism of TCP servers, where the SSL context caching logic fails to properly manage memory when encountering unknown server names.
When a TCP server with TLS and SNI enabled receives a client hello message containing an unrecognized server name, the server falls back to using the default certificate. However, the SSL context created during this process is incorrectly stored in the server name map without proper bounds checking or cleanup. Each unique fake server name results in a new cache entry, allowing an attacker to systematically fill the JVM heap memory.
Root Cause
The root cause is improper memory management in the SNI certificate lookup mechanism. When the Vert.x server encounters an unknown SNI hostname, it correctly falls back to the default certificate but mistakenly caches the resulting SSL context keyed by the unrecognized hostname. Since there are virtually unlimited possible fake hostnames an attacker can generate, this caching behavior creates an unbounded memory growth pattern that cannot be mitigated by standard JVM garbage collection.
Attack Vector
The attack exploits the network-accessible TLS handshake process. An attacker does not require authentication to exploit this vulnerability - they simply need to establish TCP connections to the vulnerable server and initiate TLS handshakes with varying fake SNI server names. Each malicious client hello message contributes to memory exhaustion.
The attack sequence involves:
- Establishing a TCP connection to the vulnerable Vert.x server
- Sending a TLS client hello message with a unique, fake SNI hostname
- Repeating the process with different fake hostnames until the JVM exhausts available heap memory
- The server becomes unresponsive due to OutOfMemoryError
Since this is a network-based attack requiring low complexity and no privileges, it can be executed remotely against any exposed Vert.x TCP server with TLS and SNI enabled.
Detection Methods for CVE-2024-1300
Indicators of Compromise
- Unusual increase in JVM heap memory usage on servers running Vert.x applications
- OutOfMemoryError exceptions in application logs without corresponding application-level memory pressure
- High volume of TLS handshake attempts from single or multiple sources
- Abnormal growth in SSL context cache entries in Vert.x server metrics
Detection Strategies
- Monitor JVM heap usage patterns for steady, unbounded growth on Vert.x servers
- Implement alerting on TLS handshake failure rates that may indicate exploitation attempts
- Analyze network traffic for anomalous patterns of TLS client hello messages with varying SNI values
- Review application logs for memory-related warnings and OutOfMemoryError stack traces
Monitoring Recommendations
- Configure JVM memory monitoring with threshold-based alerts for Vert.x applications
- Enable detailed TLS handshake logging to capture SNI hostname information
- Implement rate limiting on TLS connection attempts at the network or application layer
- Deploy SentinelOne Singularity Platform for real-time behavioral monitoring of Java application memory patterns
How to Mitigate CVE-2024-1300
Immediate Actions Required
- Update Eclipse Vert.x to the latest patched version that addresses CVE-2024-1300
- Apply relevant Red Hat security advisories for affected Red Hat products
- Implement network-level rate limiting for incoming TLS connections
- Monitor JVM memory usage closely during patch deployment windows
Patch Information
Multiple Red Hat security advisories address this vulnerability across various products. Organizations using Red Hat distributions should apply the following updates:
- RHSA-2024:1662
- RHSA-2024:1706
- RHSA-2024:1923
- RHSA-2024:2088
- RHSA-2024:2833
- RHSA-2024:3527
- RHSA-2024:3989
- RHSA-2024:4884
For additional technical details, refer to the Red Hat CVE-2024-1300 Details and Vert.x SNI Documentation.
Workarounds
- Disable SNI support on Vert.x TCP servers if not required for application functionality
- Implement a reverse proxy or load balancer with SNI validation to filter requests before they reach Vert.x
- Configure JVM heap limits with appropriate garbage collection tuning to delay memory exhaustion
- Deploy network-level controls to restrict TLS connection rates from individual source addresses
# Example JVM configuration to increase heap monitoring
# Add to Vert.x application startup parameters
-XX:+HeapDumpOnOutOfMemoryError
-XX:HeapDumpPath=/var/log/vert.x/heapdumps
-Xmx4g
-XX:+UseG1GC
-XX:MaxGCPauseMillis=200
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
