CVE-2025-12205 identifies a use-after-free vulnerability in Kamailio version 5.5, a widely used open-source SIP server for handling VoIP signaling. The vulnerability resides in the sr_push_yy_state function within the src/core/cfg.lex file, which is part of the Configuration File Handler component. Use-after-free errors occur when a program continues to use memory after it has been freed, potentially leading to memory corruption, crashes, or arbitrary code execution. In this case, the flaw can be triggered by a local attacker with limited privileges (PR:L) without requiring user interaction (UI:N). The CVSS vector indicates low attack complexity (AC:L) but requires local access (AV:L), and the impact on confidentiality, integrity, and availability is limited but non-negligible (VC:L, VI:L, VA:L). The vulnerability is exploitable due to improper memory management during configuration file parsing, which could allow an attacker to manipulate the program state or cause denial of service. Although exploit code has been published, no confirmed exploitation in the wild has been reported. The vendor has not issued a patch or responded to the disclosure, increasing the urgency for organizations to implement compensating controls. Kamailio is commonly deployed in telecommunication environments, making this vulnerability relevant for VoIP infrastructure security.

For European organizations, especially telecom providers and enterprises relying on Kamailio 5.5 for VoIP services, this vulnerability poses a moderate risk. Exploitation could lead to denial of service or partial compromise of system integrity, potentially disrupting voice communications and related services. Confidentiality impacts are limited but could expose sensitive signaling information if exploited. The requirement for local access reduces the risk of remote exploitation but raises concerns about insider threats or compromised local accounts. Disruption of VoIP infrastructure can have significant operational and reputational consequences, particularly for critical communication providers and emergency services. The lack of vendor response and patches increases exposure time, necessitating proactive risk management. Organizations with strict regulatory requirements for telecom security in Europe must consider this vulnerability in their risk assessments and incident response planning.

Given the absence of an official patch, European organizations should implement the following specific mitigations: 1) Restrict local access to Kamailio servers by enforcing strict access controls, limiting user accounts with local privileges, and employing multi-factor authentication for administrative access. 2) Monitor system logs and configuration file changes for unusual activity that could indicate exploitation attempts. 3) Employ application whitelisting and runtime protections to detect and prevent abnormal process behavior. 4) Isolate Kamailio servers within secure network segments to reduce the risk of lateral movement from compromised hosts. 5) Regularly audit and harden the underlying operating system and services to minimize the attack surface. 6) Plan for an upgrade to a patched Kamailio version once available or consider temporary mitigations such as disabling or restricting the vulnerable configuration handler if feasible. 7) Conduct internal security awareness training to reduce insider threat risks. 8) Engage with the Kamailio community or security forums for updates and potential unofficial patches or workarounds.