CVE-2024-47619 is a high-severity vulnerability affecting syslog-ng versions prior to 4.8.2. syslog-ng is a widely used enhanced logging daemon that supports secure transmission of log data using TLS. The vulnerability stems from improper certificate validation in the function tls_wildcard_match(), which incorrectly allows wildcard certificates such as 'foo.*.bar' and partial wildcards like 'foo.a*c.bar'. According to TLS standards, such wildcard patterns are invalid and should be rejected. However, due to this flawed validation, syslog-ng may accept TLS certificates that do not strictly match the intended domain names. This weakness can be exploited by an attacker to perform man-in-the-middle (MITM) attacks by presenting a malicious certificate that passes the flawed validation, thereby intercepting or altering log data transmitted over TLS. The vulnerability does not require authentication or user interaction and can be exploited remotely over the network. The issue was fixed in syslog-ng version 4.8.2 by correcting the wildcard matching logic to comply with proper certificate validation standards. The CVSS v3.1 base score is 7.5 (high), reflecting the network attack vector, low attack complexity, no privileges required, and no user interaction, with impact on integrity but not confidentiality or availability. Although no known exploits are reported in the wild yet, the vulnerability poses a significant risk to the integrity of log data, which is critical for security monitoring and forensic investigations. Organizations relying on syslog-ng for secure log transport should prioritize upgrading to version 4.8.2 or later to mitigate this risk.

For European organizations, the impact of this vulnerability is considerable. syslog-ng is commonly deployed in enterprise environments to centralize and secure log data from various systems. If exploited, attackers could intercept or manipulate log messages, undermining the integrity of security logs. This compromises incident detection, response, and auditing capabilities, potentially allowing attackers to hide malicious activities or tamper with forensic evidence. Critical sectors such as finance, healthcare, government, and critical infrastructure in Europe rely heavily on trustworthy logging for compliance with regulations like GDPR and NIS Directive. A successful MITM attack exploiting this vulnerability could lead to regulatory non-compliance, financial penalties, and reputational damage. Furthermore, altered logs could impede investigations into cyber incidents, increasing the risk of prolonged breaches. The vulnerability’s network-based exploitability and lack of required privileges make it a practical threat in environments where syslog-ng is exposed to untrusted networks or where TLS is used to secure log transport over potentially hostile networks.

To mitigate this vulnerability, European organizations should immediately upgrade all syslog-ng installations to version 4.8.2 or later, where the certificate validation logic has been corrected. In addition to patching, organizations should audit their syslog-ng configurations to ensure TLS is properly enforced and that certificates used for TLS connections adhere strictly to valid wildcard patterns as per RFC 6125. Network segmentation should be employed to restrict syslog-ng traffic to trusted network segments, minimizing exposure to untrusted networks. Implementing mutual TLS authentication can further strengthen trust between log senders and receivers. Monitoring and alerting on anomalous certificate usage or unexpected TLS connection patterns can help detect potential exploitation attempts. Finally, organizations should review and enhance their incident response plans to consider scenarios involving log tampering or interception, ensuring rapid detection and remediation.