A stack buffer overflow vulnerability in the PJSIP multimedia communication library poses a high risk of application-level denial of service for systems processing registration responses.

This is a stack-based buffer overflow (CWE-121) located in the update_service_route function of pjsua_acc.c. The vulnerability is exploitable by an unauthenticated attacker, such as a malicious or compromised registrar, by providing a 2xx registration response containing an unbounded number of Service-Route headers.

The vulnerability carries a CVSS score of 8.8, reflecting its high potential for service disruption. Successful exploitation results in an application crash, causing significant downtime for communication services relying on the PJSUA API. While the primary impact is denial of service, the nature of stack-based memory corruption leaves the possibility of more severe exploitation vectors, such as arbitrary code execution, which could lead to unauthorized system access or data compromise.

Immediate Action: Update the PJSIP library to the version containing the fix for commit acc03b57cef7a7d31b8e1f5b9117437d7e87c591.

Proactive Monitoring: Review SIP registration logs for unusual traffic patterns or responses from registrars that deviate from expected header counts.

Compensating Controls: Implement strict validation of SIP responses at the network edge or via a Session Border Controller to filter out malformed or excessively large registration headers.

Public Exploit Available: Unknown

Given the high CVSS severity and the critical role of multimedia libraries in communication infrastructure, organizations must prioritize patching this flaw. Administrators should verify their current library version against the fixed commit identifier and apply the necessary updates to prevent potential service instability and exploitation.