CVE-2025-12205 identifies a use-after-free vulnerability in Kamailio version 5.5, specifically within the function sr_push_yy_state located in src/core/cfg.lex, part of the configuration file handler component. Use-after-free vulnerabilities occur when a program continues to use memory after it has been freed, potentially leading to arbitrary code execution, crashes, or data corruption. In this case, the vulnerability arises from improper handling of state transitions during configuration file parsing. Exploitation requires local attacker privileges to manipulate configuration files, which means remote exploitation is not feasible without prior local access. The vulnerability has a CVSS 4.8 score, reflecting medium severity due to the limited attack vector (local access required) and the complexity of exploitation (manipulating config files). The vendor has not issued a patch or responded to the disclosure, and while a public exploit exists, its practical impact is mitigated by the attack prerequisites. The vulnerability could allow an attacker with local access to cause denial of service or potentially execute arbitrary code by exploiting the use-after-free condition during configuration reload or parsing. Given Kamailio's role as a SIP server widely used in VoIP infrastructures, this vulnerability could impact telecommunication services if exploited.

For European organizations, particularly those operating VoIP services or telecommunication infrastructure using Kamailio 5.5, this vulnerability poses a risk of service disruption or potential privilege escalation if an attacker gains local access. The impact on confidentiality is limited unless the attacker leverages the vulnerability to execute arbitrary code and access sensitive data. Integrity and availability could be compromised through crashes or manipulation of configuration states, leading to denial of service. Since exploitation requires local access and configuration file manipulation, the threat is primarily to internal systems or environments where attackers have already penetrated perimeter defenses. However, in multi-tenant or shared hosting environments, this could facilitate lateral movement or escalation. The lack of vendor response and patches increases the risk window. European telecom providers and enterprises relying on Kamailio for SIP routing should consider this vulnerability in their risk assessments and incident response planning.

1. Restrict local access to systems running Kamailio 5.5 to trusted administrators only, enforcing strict access controls and monitoring. 2. Implement file integrity monitoring on Kamailio configuration files to detect unauthorized changes promptly. 3. Use host-based intrusion detection systems (HIDS) to alert on suspicious activities related to configuration file access or modification. 4. Isolate Kamailio servers in secure network segments to limit exposure and reduce the risk of local compromise. 5. Regularly audit user accounts and permissions on Kamailio hosts to ensure minimal privilege principles are enforced. 6. Prepare for patch deployment by monitoring vendor communications and community advisories, applying updates immediately when available. 7. Consider upgrading to later Kamailio versions if they address this or related vulnerabilities. 8. Employ runtime application self-protection (RASP) or sandboxing techniques where feasible to mitigate exploitation impact. 9. Conduct penetration testing and vulnerability assessments focusing on local privilege escalation vectors to identify potential attack paths.