CVE-2022-42905 is a critical security vulnerability identified in wolfSSL versions prior to 5.5.2. wolfSSL is a widely used lightweight SSL/TLS library designed for embedded systems and applications requiring secure communications. This vulnerability arises when the WOLFSSL_CALLBACKS flag is enabled, a feature intended solely for debugging purposes. Under these conditions, a malicious TLS 1.3 client or an attacker positioned on the network can exploit the flaw to trigger a buffer over-read on the heap by 5 bytes. A buffer over-read occurs when a program reads more data than the allocated buffer size, potentially exposing sensitive information stored adjacent to the buffer in memory. The vulnerability is classified under CWE-125 (Out-of-bounds Read). The CVSS v3.1 score for this vulnerability is 9.1, indicating a critical severity level. The vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H) reveals that the attack can be executed remotely over the network without any privileges or user interaction, leading to high confidentiality impact and high availability impact, but no impact on integrity. Although no known exploits have been reported in the wild, the ease of exploitation combined with the critical score necessitates urgent attention. The vulnerability specifically affects TLS 1.3 connections when debugging callbacks are enabled, which is not typical in production environments but may be present in development or testing setups or inadvertently enabled in some deployments.

For European organizations, the impact of CVE-2022-42905 can be significant, especially for those relying on wolfSSL in embedded devices, IoT infrastructure, or secure communication modules. The buffer over-read can lead to leakage of sensitive memory contents, potentially exposing cryptographic keys, user data, or other confidential information. This compromises confidentiality and can facilitate further attacks such as session hijacking or man-in-the-middle attacks. Additionally, the vulnerability causes a high availability impact, which may result in service disruptions or denial of service conditions if exploited at scale. Organizations in sectors such as telecommunications, industrial control systems, automotive, healthcare, and critical infrastructure—where embedded systems and secure communications are prevalent—are particularly at risk. Given the remote and unauthenticated nature of the exploit, attackers can target vulnerable systems from anywhere, increasing the threat surface. The absence of known exploits in the wild provides a window for proactive mitigation, but the critical severity demands immediate patching or configuration changes to prevent potential exploitation.

1. Immediate upgrade to wolfSSL version 5.5.2 or later, where this vulnerability is patched, is the most effective mitigation. 2. Disable the WOLFSSL_CALLBACKS flag in all production and non-debugging environments to prevent the vulnerable code path from being active. 3. Conduct an inventory of all embedded devices and applications using wolfSSL to identify potentially vulnerable instances, including those in development or testing environments that might be exposed. 4. Implement network-level protections such as TLS inspection and anomaly detection to monitor for unusual TLS 1.3 client behavior indicative of exploitation attempts. 5. Employ strict network segmentation to isolate embedded devices and reduce exposure to untrusted networks. 6. Regularly update and audit device firmware and software to ensure timely application of security patches. 7. Educate development and operations teams about the risks of enabling debugging features like WOLFSSL_CALLBACKS in production to prevent inadvertent exposure.