CVE-2025-47779 is a high-severity vulnerability affecting multiple versions of Asterisk, an open-source private branch exchange (PBX) widely used for telephony services. The flaw arises from improper neutralization of delimiters in SIP MESSAGE requests (as defined in RFC 3428), specifically in the authentication handling process. Prior to fixed versions (18.26.2, 20.14.1, 21.9.1, 22.4.1 and certified-asterisk versions 18.9-cert14 and 20.7-cert5), authenticated attackers can exploit this vulnerability to spoof any user identity within the system. This allows them to send spam or fake chat messages that appear to originate from trusted users or administrators. The vulnerability does not affect confidentiality directly but severely impacts integrity by enabling message spoofing and social engineering attacks such as phishing. The vulnerability requires the attacker to have some level of authentication (PR:L) but no user interaction is needed (UI:N), and it can be exploited remotely over the network (AV:N). The scope is changed (S:C), meaning the attack can affect resources beyond the initially vulnerable component. The CVSS score is 7.7 (high), reflecting the significant risk posed by this issue. Although no known exploits are currently reported in the wild, the potential for abuse is considerable, especially in environments where Asterisk is used for internal communication and telephony. The root cause relates to CWE-140 (Improper Neutralization of Delimiters) and CWE-792 (Exposure to External Control of Critical State Data), indicating that the system fails to properly sanitize or validate input delimiters in SIP messages, leading to spoofing capabilities. The vulnerability impacts all affected versions prior to the patches, and administrators following best practices can still be targeted, highlighting the criticality of applying updates promptly.

For European organizations, the impact of CVE-2025-47779 can be significant, especially for enterprises, service providers, and government agencies relying on Asterisk-based telephony and messaging systems. Spoofed messages can undermine trust within communication channels, facilitating phishing, social engineering, and spam campaigns that may lead to credential theft, fraud, or unauthorized access to sensitive information. The integrity of internal communications can be compromised, potentially disrupting business operations and damaging reputations. Since Asterisk is often used in call centers, emergency services, and corporate environments, exploitation could also lead to operational disruptions or misrouting of critical communications. The vulnerability's ability to spoof administrator identities further elevates the risk, as attackers could manipulate system configurations or deceive users into executing malicious actions. Given the interconnected nature of European telecommunication infrastructure and regulatory emphasis on data protection (e.g., GDPR), such attacks could also result in compliance violations and financial penalties.

European organizations should prioritize upgrading Asterisk installations to the fixed versions: 18.26.2, 20.14.1, 21.9.1, 22.4.1, or the corresponding certified-asterisk patched versions (18.9-cert14, 20.7-cert5). Beyond patching, administrators should implement strict authentication controls to limit access to SIP MESSAGE functionalities only to trusted users and devices. Network segmentation can reduce exposure by isolating PBX systems from general user networks. Monitoring and logging SIP MESSAGE traffic for anomalies or unexpected sender identities can help detect exploitation attempts early. Employing SIP message validation tools or intrusion detection systems tailored to VoIP protocols can further mitigate risks. User awareness training focused on recognizing phishing and social engineering attempts via telephony or chat messages is also critical. Finally, organizations should review and harden their PBX configurations to disable unnecessary features and enforce least privilege principles for all users interacting with the system.