Executive brief
PJSIP is a multimedia communication library used by voice and video calling applications to handle SIP registration and call setup. When registering with a SIP server, a malicious or compromised server can send an excessive number of Service-Route headers that overflow an internal buffer, causing the application to crash (denial of service) or potentially allowing memory corruption attacks.
Technical details
A stack-based buffer overflow vulnerability exists in the update_service_route() function in pjsua_acc.c. The function stores Service-Route URIs from REGISTER responses into a fixed-size array (PJ_ARRAY_SIZE(uri)) without properly bounding the number of headers processed. An attacker controlling or spoofing a SIP registrar can send a 2xx REGISTER response with more than the maximum allowed Service-Route headers, causing writes past the array boundary. The overwritten values are internal pointers rather than attacker-controlled data, making denial of service the primary impact, though memory corruption is not excluded. The attack requires network-level access to intercept or spoof the registrar response (possible over unprotected transports like UDP). The vulnerability has been patched in commit acc03b5 by adding bounds checks before each array write.
Affected products
- PJSIP pjproject 2.17 and earlier
Timeline
- 2026-09-04: disclosed
- 2026-06-17: patched: Patched via commit acc03b5 in master branch