CVE-2024-0901: WolfSSL DoS Vulnerability

CVE-2024-0901 Overview

CVE-2024-0901 is an out-of-bounds read vulnerability in wolfSSL that allows remote attackers to crash applications or potentially leak sensitive memory contents by sending specially crafted malformed packets with correct length fields. This vulnerability affects the wolfSSL cryptographic library, which is widely used in embedded systems, IoT devices, and security-critical applications.

Critical Impact

Remote attackers can crash wolfSSL-enabled applications or potentially extract sensitive information from memory through out-of-bounds read operations without requiring authentication.

Affected Products

• wolfSSL wolfssl (all affected versions prior to patch)

Discovery Timeline

• 2024-03-25 - CVE CVE-2024-0901 published to NVD
• 2025-12-15 - Last updated in NVD database

Technical Details for CVE-2024-0901

Vulnerability Analysis

This vulnerability stems from improper validation of array index (CWE-129) within wolfSSL's packet processing logic. When processing incoming network packets, the library fails to properly validate array boundaries despite the packet having a syntactically correct length field. This disconnect between length validation and actual data access creates a dangerous security gap.

The vulnerability can be exploited remotely over the network without requiring any user interaction or authentication. An attacker can craft a malformed packet that passes initial length checks but triggers an out-of-bounds memory read during subsequent processing, leading to either a SEGV (segmentation violation) crash or unauthorized access to adjacent memory regions.

The impact is twofold: availability is compromised through application crashes (denial of service), and confidentiality may be breached if the out-of-bounds read returns sensitive data from memory that could be exfiltrated back to the attacker.

Root Cause

The root cause is improper validation of array index (CWE-129). The vulnerability exists because the packet parsing code trusts the length field in incoming packets to bound array accesses, but a malformed packet can specify indices or offsets that point outside the allocated buffer boundaries. The code fails to verify that derived array indices remain within valid bounds before accessing memory, allowing attackers to manipulate packet contents to trigger out-of-bounds memory operations.

Attack Vector

The attack can be executed remotely over the network without any privileges or user interaction. An attacker sends a specially crafted TLS/SSL packet to a wolfSSL-enabled server or client application. The packet is constructed with a valid length header that passes initial validation, but contains malformed internal structure that causes the parser to calculate invalid array indices during subsequent processing.

When the vulnerable code attempts to read from these calculated positions, it accesses memory outside the intended buffer boundaries, resulting in either a crash (SEGV) or disclosure of adjacent memory contents. This attack requires network access to the target application but no authentication or special privileges.

Detection Methods for CVE-2024-0901

Indicators of Compromise

• Unexpected application crashes or SEGV signals in wolfSSL-linked processes
• Anomalous TLS handshake failures with malformed packet indicators in logs
• Memory corruption warnings or segmentation faults in system logs
• Unusual network traffic patterns with malformed TLS/SSL packets

Detection Strategies

• Monitor for repeated SEGV or crash events in applications using wolfSSL
• Implement network intrusion detection rules for malformed TLS/SSL packet structures
• Deploy application crash monitoring with stack trace analysis
• Review wolfSSL library versions across the environment to identify vulnerable deployments

Monitoring Recommendations

• Enable verbose logging for TLS/SSL connections to capture packet processing anomalies
• Configure system monitoring to alert on repeated application crashes
• Implement memory access violation detection in production environments
• Monitor network traffic for unusual packet lengths or malformed TLS handshakes

How to Mitigate CVE-2024-0901

Immediate Actions Required

• Identify all applications and systems using wolfSSL library
• Review the GitHub Pull Request #7099 for patch details
• Apply the security patch from the official wolfSSL repository
• Restart all affected applications after patching

Patch Information

The vulnerability has been addressed in the wolfSSL repository. Security teams should apply the fix available in GitHub Pull Request #7099. This patch addresses the improper array index validation that allowed the out-of-bounds read condition. Organizations should update to the latest wolfSSL version that includes this fix.

For additional technical context, refer to GitHub Issue #7089 which documents the vulnerability details.

Workarounds

• Implement network-level filtering to drop malformed TLS/SSL packets before they reach vulnerable applications
• Deploy a Web Application Firewall (WAF) or reverse proxy that performs deep packet inspection on TLS traffic
• Consider temporarily restricting network access to critical wolfSSL-enabled services until patching is complete
• Enable address space layout randomization (ASLR) and other memory protection mechanisms to reduce exploitation impact