CVE-2024-2511: OpenSSL TLSv1.3 Memory DoS Vulnerability

CVE-2024-2511 is a denial of service vulnerability in OpenSSL TLSv1.3 that causes unbounded memory growth in misconfigured servers. Attackers can trigger session cache failures leading to DoS. This article covers technical details, affected configurations, impact assessment, and mitigation strategies.

CVE-2024-2511 Overview

Issue summary: Some non-default TLS server configurations can cause unbounded memory growth when processing TLSv1.3 sessions. This problem can result in a Denial of Service (DoS) attack due to unbounded memory growth on certain TLSv1.3 server configurations without default anti-replay protections.

Critical Impact
An attacker may exploit certain server configurations to trigger unbounded memory growth that would lead to a Denial of Service.

Affected Products

Not Available

Discovery Timeline

2024-04-08 - CVE CVE-2024-2511 published to NVD
2025-11-03 - Last updated in NVD database

Technical Details for CVE-2024-2511

Vulnerability Analysis

In TLSv1.3, the SSL_OP_NO_TICKET option when used without early data support and default anti-replay features can cause the session cache to enter an incorrect state, failing to flush as required. This may lead to unbounded memory growth.

Root Cause

The vulnerability occurs due to improper handling of session cache flushing in specific configurations, leading to excessive memory consumption.

Attack Vector

Network

// Example exploitation code (sanitized)
void triggerDoS() {
    while(true) {
        // Simulate session creation causing memory growth
        initiateTLSSession();
    }
}

Detection Methods for CVE-2024-2511

Indicators of Compromise

Unusual memory consumption
Repeated session creation logs
Out-of-memory errors

Detection Strategies

Implement network monitoring to detect abnormal memory usage patterns and excessive session creations. Utilize SIEM solutions for correlating these events.

Monitoring Recommendations

Use memory profiling tools to detect unusual growth
Log and alert on repeated TLS session initiations exceeding baseline

How to Mitigate CVE-2024-2511

Immediate Actions Required

Disable non-default configurations causing the issue
Enable default anti-replay protections
Monitor memory usage continuously

Patch Information

Refer to OpenSSL security advisory for updates and patches.

Workarounds

Avoid using SSL_OP_NO_TICKET without early_data support.

bash

# Configuration example
echo "Configuring safe TLS settings"
ssl_conf="default"
security_level="high"
# Ensure the correct settings are applied
echo $ssl_conf