Executive Summary

This vulnerability, identified as CVE-2026-5393, is an out-of-bounds read issue that occurs when processing a dual-algorithm CertificateVerify message in the wolfSSL library. Specifically, it happens if the wolfSSL library is built with the experimental and dual-algorithm certificate options enabled (--enable-experimental and --enable-dual-alg-certs). An attacker can craft input that causes the software to read memory outside the intended bounds, potentially leading to security and stability problems.

The issue is related to insufficient bounds checking when parsing certificates with dual-algorithm signatures, which can cause the program to access invalid memory locations.

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Impact Analysis

This vulnerability can impact you by causing the wolfSSL library to perform out-of-bounds memory reads, which may lead to crashes, memory corruption, or exposure of sensitive information. Such behavior can undermine the security and stability of applications relying on wolfSSL for TLS communication.

Exploitation requires the library to be built with specific experimental features enabled, but if exploited, it could allow attackers to disrupt secure communications or potentially extract sensitive data from memory.

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Mitigation Strategies

To mitigate this vulnerability, you should update wolfSSL to version 5.9.1 or later, which includes fixes that add bounds checks and prevent out-of-bounds reads when processing dual-algorithm CertificateVerify messages.

Additionally, avoid building wolfSSL with the --enable-experimental and --enable-dual-alg-certs options enabled unless necessary, as the vulnerability only occurs when these options are used.

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Compliance Impact

The provided information does not specify how the CVE-2026-5393 vulnerability affects compliance with common standards and regulations such as GDPR or HIPAA.

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Detection Guidance

This vulnerability occurs specifically when wolfSSL is built with the --enable-experimental and --enable-dual-alg-certs options enabled. Detection involves identifying if your wolfSSL build includes these options and if it processes dual-algorithm CertificateVerify messages.

Since the vulnerability is triggered by crafted dual-algorithm CertificateVerify messages causing out-of-bounds reads, monitoring network traffic for such unusual or malformed TLS handshake messages could help detect exploitation attempts.

There are no explicit commands provided in the available resources for detecting this vulnerability directly. However, general approaches include:

• Checking the wolfSSL version and build configuration to confirm if --enable-experimental and --enable-dual-alg-certs were used.
• Using network packet capture tools (e.g., tcpdump, Wireshark) to analyze TLS handshakes for dual-algorithm CertificateVerify messages.
• Reviewing application logs for crashes or errors related to TLS certificate verification.

Example commands that might assist in detection include:

• To check wolfSSL version and build options (if accessible): `wolfssl-version` or inspecting build logs.
• To capture TLS traffic on port 443: `tcpdump -i <interface> -w capture.pcap port 443`
• To analyze captured traffic for CertificateVerify messages: open capture.pcap in Wireshark and filter with `tls.handshake.type == 15` (CertificateVerify message type).

Since no direct detection scripts or commands are provided in the resources, these general methods are recommended.

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